[build] Set MSVS .obj folders in gyp for v8_base

Building on Windows with gyp fails depending on the result from
sharding the src/v8.gyp:v8_base target. If two source files with the
same name are in the same shard, their output object file path would
conflict with one another. One example of this conflict is v8_base's
runtime/runtime.cc and the V8 inspector's protocol/Runtime.cpp that
is generated at build time, for which the files runtime.obj and
Runtime.obj would be created, but MSVS overwrites one of them with
the other.

Dividing the .obj output path by the original source's extension
prevents this overwrite.

Refs: nodejs/node#13959
Bug: 
Change-Id: I158e6178f2511297899ee50ea159f574916f903f
Reviewed-on: https://chromium-review.googlesource.com/556599
Reviewed-by: Michael Achenbach <[email protected]>
Commit-Queue: Michael Achenbach <[email protected]>
Cr-Commit-Position: refs/heads/master@{#46354}

Author: jaimecbernardo

AUTHORS

@@ -70,6 +70,7 @@ Hirofumi Mako <[email protected]>
 Honggyu Kim <[email protected]>
 Ioseb Dzmanashvili <[email protected]>
 Isiah Meadows <[email protected]>
+Jaime Bernardo <[email protected]>
 Jan de Mooij <[email protected]>
 Jay Freeman <[email protected]>
 James Pike <[email protected]>

src/v8.gyp

@@ -1803,6 +1803,13 @@
           # limit. This breaks it into multiple pieces to avoid the limit.
           # See http://crbug.com/485155.
           'msvs_shard': 4,
+          # This will prevent V8's .cc files conflicting with the inspector's
+          # .cpp files in the same shard.
+          'msvs_settings': {
+            'VCCLCompilerTool': {
+              'ObjectFile':'$(IntDir)%(Extension)\\',
+            },
+          },
         }],
         ['component=="shared_library"', {
           'defines': [