Revert 'gn: cross-platform exception disable'

This reverts commit 4923e3cfbc2b617614858c427fa87a8c67aca784.

Since exceptions are in the process of being removed,
and the code currently isn't rollable into pdfium (for other
reasons) I'm going to revert this for now, so that this CL
doesn't become blocking-for-rolls if the other min/max problem
is addressed.

And, hopefully by the time I get back to this it won't be
necessary anyway.

BUG=pdfium:28,pdfium:31,chromium:354261
R=thakis@chromium.org

Review URL: https://codereview.chromium.org/432243002

BUILD.gn

diff --git a/BUILD.gn b/BUILD.gn
index f562c1e..9ecd708 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -85,8 +85,9 @@
 
   libs = []
   configs -= [ "//build/config/compiler:chromium_code" ]
-  configs -= [ "//build/config/compiler:no_exceptions" ]
-  configs += [ "//build/config/compiler:exceptions" ]
+  if (is_posix) {
+    configs -= [ "//build/config/gcc:no_exceptions" ]
+  }
   configs += [ ":pdfium_config", "//build/config/compiler:no_chromium_code" ]
 
   deps = [
@@ -137,8 +138,9 @@
     "core/src/fdrm/crypto/fx_crypt_sha.cpp",
   ]
   configs -= [ "//build/config/compiler:chromium_code" ]
-  configs -= [ "//build/config/compiler:no_exceptions" ]
-  configs += [ "//build/config/compiler:exceptions" ]
+  if (is_posix) {
+    configs -= [ "//build/config/gcc:no_exceptions" ]
+  }
   configs += [ ":pdfium_config", "//build/config/compiler:no_chromium_code" ]
 }
 
@@ -168,8 +170,9 @@
     "core/src/fpdfdoc/tagged_int.h",
   ]
   configs -= [ "//build/config/compiler:chromium_code" ]
-  configs -= [ "//build/config/compiler:no_exceptions" ]
-  configs += [ "//build/config/compiler:exceptions" ]
+  if (is_posix) {
+    configs -= [ "//build/config/gcc:no_exceptions" ]
+  }
   configs += [ ":pdfium_config", "//build/config/compiler:no_chromium_code" ]
 }
 
@@ -294,8 +297,9 @@
     "core/src/fpdfapi/fpdf_render/render_int.h",
   ]
   configs -= [ "//build/config/compiler:chromium_code" ]
-  configs -= [ "//build/config/compiler:no_exceptions" ]
-  configs += [ "//build/config/compiler:exceptions" ]
+  if (is_posix) {
+    configs -= [ "//build/config/gcc:no_exceptions" ]
+  }
   configs += [ ":pdfium_config", "//build/config/compiler:no_chromium_code" ]
 }
 
@@ -311,8 +315,9 @@
     "core/src/fpdftext/unicodenormalizationdata.cpp",
   ]
   configs -= [ "//build/config/compiler:chromium_code" ]
-  configs -= [ "//build/config/compiler:no_exceptions" ]
-  configs += [ "//build/config/compiler:exceptions" ]
+  if (is_posix) {
+    configs -= [ "//build/config/gcc:no_exceptions" ]
+  }
   configs += [ ":pdfium_config", "//build/config/compiler:no_chromium_code" ]
 }
 
@@ -479,8 +484,9 @@
     "core/src/fxcodec/libjpeg/transupp.h",
   ]
   configs -= [ "//build/config/compiler:chromium_code" ]
-  configs -= [ "//build/config/compiler:no_exceptions" ]
-  configs += [ "//build/config/compiler:exceptions" ]
+  if (is_posix) {
+    configs -= [ "//build/config/gcc:no_exceptions" ]
+  }
 
   if (is_posix) {
     # core/src/fxcodec/fx_libopenjpeg/src/fx_mct.c does an pointer-to-int
@@ -532,8 +538,9 @@
     "core/src/fxcrt/xml_int.h",
   ]
   configs -= [ "//build/config/compiler:chromium_code" ]
-  configs -= [ "//build/config/compiler:no_exceptions" ]
-  configs += [ "//build/config/compiler:exceptions" ]
+  if (is_posix) {
+    configs -= [ "//build/config/gcc:no_exceptions" ]
+  }
   configs += [ ":pdfium_config", "//build/config/compiler:no_chromium_code" ]
 }
 
@@ -639,8 +646,9 @@
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
-  configs -= [ "//build/config/compiler:no_exceptions" ]
-  configs += [ "//build/config/compiler:exceptions" ]
+  if (is_posix) {
+    configs -= [ "//build/config/gcc:no_exceptions" ]
+  }
   configs += [ ":pdfium_config", "//build/config/compiler:no_chromium_code" ]
 
   if (pdf_use_skia) {
@@ -691,8 +699,9 @@
     "fpdfsdk/src/fxedit/fxet_pageobjs.cpp",
   ]
   configs -= [ "//build/config/compiler:chromium_code" ]
-  configs -= [ "//build/config/compiler:no_exceptions" ]
-  configs += [ "//build/config/compiler:exceptions" ]
+  if (is_posix) {
+    configs -= [ "//build/config/gcc:no_exceptions" ]
+  }
   configs += [ ":pdfium_config", "//build/config/compiler:no_chromium_code" ]
 }
 
@@ -736,8 +745,9 @@
     "fpdfsdk/src/pdfwindow/PWL_Wnd.cpp",
   ]
   configs -= [ "//build/config/compiler:chromium_code" ]
-  configs -= [ "//build/config/compiler:no_exceptions" ]
-  configs += [ "//build/config/compiler:exceptions" ]
+  if (is_posix) {
+    configs -= [ "//build/config/gcc:no_exceptions" ]
+  }
   configs += [ ":pdfium_config", "//build/config/compiler:no_chromium_code" ]
 }
 
@@ -788,8 +798,9 @@
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
-  configs -= [ "//build/config/compiler:no_exceptions" ]
-  configs += [ "//build/config/compiler:exceptions" ]
+  if (is_posix) {
+    configs -= [ "//build/config/gcc:no_exceptions" ]
+  }
   configs += [ ":pdfium_config", "//build/config/compiler:no_chromium_code" ]
   include_dirs = [
     "//v8",
@@ -808,8 +819,9 @@
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
-  configs -= [ "//build/config/compiler:no_exceptions" ]
-  configs += [ "//build/config/compiler:exceptions" ]
+  if (is_posix) {
+    configs -= [ "//build/config/gcc:no_exceptions" ]
+  }
   configs += [ ":pdfium_config", "//build/config/compiler:no_chromium_code" ]
   include_dirs = [
     "//v8",
@@ -848,7 +860,8 @@
     "fpdfsdk/src/formfiller/FFL_Utils.cpp",
   ]
   configs -= [ "//build/config/compiler:chromium_code" ]
-  configs -= [ "//build/config/compiler:no_exceptions" ]
-  configs += [ "//build/config/compiler:exceptions" ]
+  if (is_posix) {
+    configs -= [ "//build/config/gcc:no_exceptions" ]
+  }
   configs += [ ":pdfium_config", "//build/config/compiler:no_chromium_code" ]
 }