Add use_system_v8 option to gyp (off by default),

as discussed in http://groups.google.com/group/v8-users/browse_thread/thread/33a69c51d8023ced

This will make it easier for Linux distributions
to ship with system-provided V8 library.

Patch by Pawel Hajdan, Jr. <phajdan.jr@chromium.org>

Review URL: http://codereview.chromium.org/6092006


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6153 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

tools/gyp/v8.gyp

@@ -27,11 +27,14 @@
 
 {
   'variables': {
+    'use_system_v8%': 0,
     'msvs_use_common_release': 0,
     'gcc_version%': 'unknown',
     'v8_target_arch%': '<(target_arch)',
     'v8_use_snapshot%': 'true',
   },
+  'conditions': [
+    ['use_system_v8==0', {
       'target_defaults': {
         'defines': [
           'ENABLE_LOGGING_AND_PROFILING',
@@ -121,10 +124,12 @@
               ['OS=="mac"', {
                 'xcode_settings': {
                   'GCC_OPTIMIZATION_LEVEL': '3',  # -O3
-              'GCC_STRICT_ALIASING': 'YES',   # -fstrict-aliasing.  Mainline gcc
+
+                  # -fstrict-aliasing.  Mainline gcc
                   # enables this at -O2 and above,
                   # but Apple gcc does not unless it
                   # is specified explicitly.
+                  'GCC_STRICT_ALIASING': 'YES',
                 },
               }],
               ['OS=="win"', {
@@ -590,8 +595,8 @@
                 '../../src/arm/virtual-frame-arm.h',
               ],
               'conditions': [
-            # The ARM assembler assumes the host is 32 bits, so force building
-            # 32-bit host tools.
+                # The ARM assembler assumes the host is 32 bits,
+                # so force building 32-bit host tools.
                 ['host_arch=="x64" and _toolset=="host"', {
                   'cflags': ['-m32'],
                   'ldflags': ['-m32'],
@@ -816,4 +821,25 @@
           ],
         },
       ],
+    }, { # use_system_v8 != 0
+      'targets': [
+        {
+          'target_name': 'v8',
+          'type': 'settings',
+          'link_settings': {
+            'libraries': [
+              '-lv8',
+            ],
+          },
+        },
+        {
+          'target_name': 'v8_shell',
+          'type': 'none',
+          'dependencies': [
+            'v8'
+          ],
+        },
+      ],
+    }],
+  ],
 }