XFA: clang-format all pdfium code.

No behavior change.

Generated by:
  find . -name '*.cpp' -o -name '*.h' | \
  grep -E -v 'third_party|thirdparties|lpng_v163|tiff_v403' | \
  xargs ../../buildtools/mac/clang-format -i
Then manually merged https://codereview.chromium.org/1269223002/

See thread "tabs vs spaces" on pdfium@googlegroups.com for discussion.

BUG=none
diff --git a/fpdfsdk/src/fpdf_searchex.cpp b/fpdfsdk/src/fpdf_searchex.cpp
index e012d30..9747316 100644
--- a/fpdfsdk/src/fpdf_searchex.cpp
+++ b/fpdfsdk/src/fpdf_searchex.cpp
@@ -8,11 +8,9 @@
 
 #include "../../core/include/fpdftext/fpdf_text.h"
 
-DLLEXPORT int STDCALL FPDFText_GetCharIndexFromTextIndex(
-    FPDF_TEXTPAGE text_page,
-    int nTextIndex)
-{
-    if (!text_page)
-        return -1;
-    return ((IPDF_TextPage*)text_page)->CharIndexFromTextIndex(nTextIndex);
+DLLEXPORT int STDCALL
+FPDFText_GetCharIndexFromTextIndex(FPDF_TEXTPAGE text_page, int nTextIndex) {
+  if (!text_page)
+    return -1;
+  return ((IPDF_TextPage*)text_page)->CharIndexFromTextIndex(nTextIndex);
 }