Disable clang's SLP vectorizer.

It currently generates invalid code, see
http://llvm.org/bugs/show_bug.cgi?id=20354

BUG=none

Review URL: https://codereview.chromium.org/393193003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@284029 0039d316-1c4b-4281-b951-d872f2087c98

build/common.gypi

@@ -3902,6 +3902,10 @@
               # code generated by flex (used in angle) contains that keyword.
               # http://crbug.com/255186
               '-Wno-deprecated-register',
+
+              # TODO(thakis): Remove once http://llvm.org/PR20354 is fixed
+              # and the fix is in chromium.
+              '-fno-slp-vectorize',
             ],
             'cflags!': [
               # Clang doesn't seem to know know this flag.
@@ -4742,6 +4746,11 @@
                 # cfe-dev discussion.
                 '-Wno-selector-type-mismatch',
               ],
+              'OTHER_CFLAGS': [
+                # TODO(thakis): Remove once http://llvm.org/PR20354 is fixed
+                # and the fix is in chromium.
+                '-fno-slp-vectorize',
+              ],
 
               'conditions': [
                 ['clang_xcode==0', {