Don't use m32 cflag for x86_64.

gyp/opts.gyp

+# Gyp file for building opts target.
 {
   # Source lists live in opts.gypi.  This makes it easier to maintain our Chrome GYP/GN setup.
   # (To be honest, I'm not sure why we need to include common.gypi.  I thought it was automatic.)
   'variables': {
     'includes': [ 'common.gypi', 'opts.gypi' ],
   },
 
   # Generally we shove things into one 'opts' target conditioned on platform.
   # If a particular platform needs some files built with different flags,
   # those become separate targets: opts_ssse3, opts_sse41, opts_neon.
 
   'targets': [
     {
       'target_name': 'opts',
       'product_name': 'skia_opts',
       'type': 'static_library',
       'standalone_static_library': 1,
       'dependencies': [
         'core.gyp:*',
         'effects.gyp:*'
       ],
       'include_dirs': [
         '../src/core',
         '../src/opts',
         '../src/utils',
         '../include/utils',
       ],
       'conditions': [
-        [ 'skia_arch_type == "x86" and skia_os != "ios"', {
+        [ '"x86" in skia_arch_type and skia_os != "ios"', {
           'cflags': [ '-msse2' ],
           'dependencies': [ 'opts_ssse3', 'opts_sse41' ],
           'sources': [ '<@(sse2_sources)' ],
         }],
 
         [ 'skia_arch_type == "mips"', {
           'conditions': [
             [ '(mips_arch_variant == "mips32r2") and (mips_dsp == 1 or mips_dsp == 2)', {
                 'sources': [ '<@(mips_dsp_sources)' ],
             },{
                 'sources': [ '<@(none_sources)' ],
             }],
           ]
         }],
 
         [ '(skia_arch_type == "arm" and arm_version < 7) \
             or (skia_os == "ios") \
-            or (skia_os == "android" and skia_arch_type not in ["x86", "arm", "mips", "arm64"])', {
+            or (skia_os == "android" \
+                and skia_arch_type not in ["x86", "x86_64", "arm", "mips", \
+                                           "arm64"])', {
           'sources': [ '<@(none_sources)' ],
         }],
 
         [ 'skia_arch_type == "arm" and arm_version >= 7', {
           # The assembly uses the frame pointer register (r7 in Thumb/r11 in
           # ARM), the compiler doesn't like that.
           'cflags!': [ '-fno-omit-frame-pointer', '-mapcs-frame', '-mapcs' ],
           'cflags':  [ '-fomit-frame-pointer' ],
           'variables': { 'arm_neon_optional%': '<(arm_neon_optional>' },
           'sources': [ '<@(armv7_sources)' ],
@@ skipping 90 matching lines @@
           ],
         }],
       ],
       'ldflags': [
         '-march=armv7-a',
         '-Wl,--fix-cortex-a8',
       ],
     },
   ],
 }