clang/win: Use /FIintrin.h instead of /FIIntrin.h

Since Windows uses a case-insensitive file system, this doesn't matter much,
but if we ever want to turn on -Wnonportable-system-include-path we'll need
this.

(clang's lib/Headers/Intrin.h was renamed to intrin.h to match the Microsoft
header in clang r272701.)

BUG=617318

Review-Url: https://codereview.chromium.org/2066213002
Cr-Original-Commit-Position: refs/heads/master@{#399912}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 4c33b455ce98383000f33e3519ab320d6b8629c0

common.gypi

@@ -5821,8 +5821,9 @@
                   '-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): Fix those files, or move this to sub-GYPs,
+                  # https://crbug.com/592745
+                  '/FIintrin.h',
 
                   # TODO(hans): Make this list shorter eventually, http://crbug.com/504657
                   '-Wno-microsoft-enum-value',  # http://crbug.com/505296

config/win/BUILD.gn

@@ -66,8 +66,9 @@ config("compiler") {
   if (is_clang) {
     cflags += [
       # Many files use intrinsics without including this header.
-      # TODO(hans): Fix those files, or move this to sub-GYPs.
-      "/FIIntrin.h",
+      # TODO(hans): Fix those files, or move this to sub-GYPs,
+      # https://crbug.com/592745
+      "/FIintrin.h",
     ]
 
     if (visual_studio_version == "2013") {