Align host and target architectures when building v8_shell.

tools/gyp/v8.gyp

Index: tools/gyp/v8.gyp
diff --git a/tools/gyp/v8.gyp b/tools/gyp/v8.gyp
index 91984d6f3fb4bbc98da5aed3158c22199abbc4ef..1d4cbfdccd3a37f966ae48a5c235e6a4465af3ed 100644
--- a/tools/gyp/v8.gyp
+++ b/tools/gyp/v8.gyp
@@ -286,6 +286,12 @@
           'conditions': [
             ['component=="shared_library"', {
               'conditions': [
+                # The ARM assembler assumes the host is 32 bits, so force building
+                # 32-bit host tools.
+                ['v8_target_arch=="arm" and host_arch=="x64" and _toolset=="host"', {
+                  'cflags': ['-m32'],
+                  'ldflags': ['-m32'],
+                }],
                 ['OS=="win"', {
                   'defines': [
                     'BUILDING_V8_SHARED',
@@ -971,6 +977,12 @@
               # This could be gotten by not setting chromium_code, if that's OK.
               'defines': ['_CRT_SECURE_NO_WARNINGS'],
             }],
+            # The ARM assembler assumes the host is 32 bits, so force building
+            # 32-bit host tools.
+            ['v8_target_arch=="arm" and host_arch=="x64" and _toolset=="host"', {
+              'cflags': ['-m32'],
+              'ldflags': ['-m32'],
+            }],
             ['v8_compress_startup_data=="bz2"', {
               'libraries': [
                 '-lbz2',