pdfium clang/win: Stop passing /FIIntrin.h

See https://codereview.chromium.org/2076483002 for a lengthy reasoning.
The two mysterious files called out there were in boringssl and nacl,
so for pdfium this should be a complete no-op.

BUG=chromium:592745

Review-Url: https://codereview.chromium.org/2096143002

build_gyp/standalone.gypi

diff --git a/build_gyp/standalone.gypi b/build_gyp/standalone.gypi
index aa3feea..b2ec4b9 100644
--- a/build_gyp/standalone.gypi
+++ b/build_gyp/standalone.gypi
@@ -319,10 +319,6 @@
               # pattern.
               '-Wno-missing-field-initializers',
 
-              # Many files use intrinsics without including this header.
-              # TODO(hans): Fix those files, or move this to sub-GYPs.
-              '/FIIntrin.h',
-
               # TODO(hans): Make this list shorter eventually, http://crbug.com/504657
               '-Qunused-arguments',  # http://crbug.com/504658
               '-Wno-microsoft-enum-value',  # http://crbug.com/505296