Disabling nacl_win64 targets when building in target_arch!=ia32 mode.

When building on windows with target_arch=x64, we no longer need win32 targets
forced to be 64-bit. This gates out these targets when target_arch!=ia32.
(Prior CL dropped the minimal set to break the dependency between these targets
and the rest of the build. This eliminates them completely.)

BUG=None
TEST=None
R=jschuh@chromium.org,thestig@chromium.org
TBR=darin@chromium.org,abodenha@chromium.org,apatrick@chromium.org,sra@chromium.org,wtc@chromium.org

Review URL: https://chromiumcodereview.appspot.com/11929039

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@177959 0039d316-1c4b-4281-b951-d872f2087c98

diff --git a/ipc/ipc.gyp b/ipc/ipc.gyp
index c56f68a4..edc53a4 100644
--- a/ipc/ipc.gyp
+++ b/ipc/ipc.gyp

@@ -141,7 +141,7 @@
     },
   ],
   'conditions': [
-    ['OS=="win"', {
+    ['OS=="win" and target_arch=="ia32"', {
       'targets': [
         {
           'target_name': 'ipc_win64',