win: Add /Zc:inline to Pro Release builds

http://msdn.microsoft.com/en-us/library/dn642448.aspx

This makes Release .objs smaller and so links faster. It was added in
Update 2, but caused the compiler to crash on Chrome building LTCG. It
seems to be OK after Update 3.

As the depot_tools Express toolchain is not yet Update 3, we don't add
the flag there.

R=jam@chromium.org
BUG=350018,402270

Review URL: https://codereview.chromium.org/474463002

Cr-Commit-Position: refs/heads/master@{#292571}

build/common.gypi

@@ -3325,6 +3325,7 @@
             ],
             'AdditionalOptions': [
                 '/d2Zi+',  # Improve debugging of Release builds.
+                '/Zc:inline',  # Remove unreferenced COMDAT (faster links).
                 '<@(win_release_extra_cflags)',
             ],
           },
@@ -5285,6 +5286,11 @@
               4702
             ],
             'msvs_settings': {
+              'VCCLCompilerTool': {
+                'AdditionalOptions!': [
+                    '/Zc:inline',  # Not supported on non-updated Express.
+                ],
+              },
               'VCLinkerTool': {
                 # Explicitly required when using the ATL with express
                 'AdditionalDependencies': ['atlthunk.lib'],