-ansi means -std=c89, so replace -std=gnu99 -ansi with it

third_party/yasm/yasm.gyp

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # The yasm build process creates a slew of small C subprograms that
 # dynamically generate files at various point in the build process.  This makes
 # the build integration moderately complex.
 #
 # There are three classes of dynamically generated files:
 #   1) C source files that should be included in the build (eg., lc3bid.c)
@@ skipping 25 matching lines @@
       'source/patched-yasm',
     ],
 
     # The cflags used by any target that will be directly linked into yasm.
     # These are specifically not used when building the subprograms.  While
     # it would probably be safe to use these flags there as well, the
     # ./configure based build does not use the same flags between the main
     # yasm executable, and its subprograms.
     'yasm_defines': ['HAVE_CONFIG_H'],
     'yasm_cflags': [
-      '-std=gnu99',
-      '-ansi',
+      '-std=c89',
       '-pedantic',
     ],
 
     # Locations for various generated artifacts.
     'shared_generated_dir': '<(SHARED_INTERMEDIATE_DIR)/third_party/yasm',
     'generated_dir': '<(INTERMEDIATE_DIR)/third_party/yasm',
 
     # Various files referenced by multiple targets.
     'version_file': 'version.mac',  # Generated by genversion.
     'genmodule_source': 'genmodule_outfile.c',
@@ skipping 523 matching lines @@
       'include_dirs': [
         '<@(yasm_include_dirs)',
 
       ],
       'cflags': [
         '-std=gnu99',
       ],
     },
   ],
 }