Add v8_os_page_size flag for cross compilation

src/v8.gyp

Index: src/v8.gyp
diff --git a/src/v8.gyp b/src/v8.gyp
index 1eb87ab51c4411992076687c202cf444fd18dd85..8445ad4e9779471478646fa41b39719b1ac09f75 100644
--- a/src/v8.gyp
+++ b/src/v8.gyp
@@ -37,6 +37,7 @@
     'v8_enable_inspector%': 0,
     'mksnapshot_exec': '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)mksnapshot<(EXECUTABLE_SUFFIX)',
     'mkpeephole_exec': '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)mkpeephole<(EXECUTABLE_SUFFIX)',
+    'v8_os_page_size%': 0,
   },
   'includes': ['../gypfiles/toolchain.gypi', '../gypfiles/features.gypi', 'inspector/inspector.gypi'],
   'targets': [
@@ -306,6 +307,9 @@
                   ['v8_vector_stores!=0', {
                     'mksnapshot_flags': ['--vector-stores'],
                   }],
+                  ['v8_os_page_size!=0', {
+                    'mksnapshot_flags': ['--v8_os_page_size', '<(v8_os_page_size)'],
+                  }],
                 ],
               },
               'conditions': [