Fix MSVC librarian warning about no target machine.

We had the appropriate setting in our linker settings, but were
missing the entry in our librarian settings. The new static lib
target exposed the error.

Change-Id: I689ccb3cd6dbf2218c869b33500aaef43b8a421f
Reviewed-on: https://chromium-review.googlesource.com/216460
Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
diff --git a/build/common.gypi b/build/common.gypi
index 173253a..b35a79e 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -151,6 +151,7 @@
                     },
                     'VCLibrarianTool':
                     {
+                        'TargetMachine': '1',
                         'AdditionalLibraryDirectories':
                         [
                             '<(windows_sdk_path)/Lib/win8/um/x86',