pdfviewer: compile pdfviewer in gm, only if the flag is set (currently we compile pdfviewer, even if it is not used)

R=scroggo@google.com, jvanverth@google.com

Author: edisonn@google.com

Review URL: https://codereview.chromium.org/68533003

git-svn-id: http://skia.googlecode.com/svn/trunk@12249 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gyp/utils.gyp b/gyp/utils.gyp
index 1725910..2133d2b 100644
--- a/gyp/utils.gyp
+++ b/gyp/utils.gyp
@@ -214,6 +214,11 @@
             '../src/utils/android/ashmem.cpp',
           ],
         }],
+        ['skia_run_pdfviewer_in_gm', {
+          'defines': [
+            'SK_BUILD_NATIVE_PDF_RENDERER',
+          ],
+        }],
       ],
       'direct_dependent_settings': {
         'include_dirs': [