Instrumented libraries: work around a build issue in pixman.

BUG=449183
TBR=glider@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/920543003

Cr-Original-Commit-Position: refs/heads/master@{#315990}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 905851b176b07d53a799d4855bcd39ce9a82831e
diff --git a/instrumented_libraries.gyp b/instrumented_libraries.gyp
index eeed377..105e9b8 100644
--- a/instrumented_libraries.gyp
+++ b/instrumented_libraries.gyp
@@ -317,6 +317,8 @@
         # From debian/rules.
         '--disable-gtk',
         '--disable-silent-rules',
+        # Avoid a clang issue. http://crbug.com/449183
+        '--disable-mmx',
       ],
       'patch': 'patches/libpixman-1-0.diff',
       'includes': ['standard_instrumented_package_target.gypi'],