Fix Mac fontconfig build (try 2)

gyp/gm.gyp

 # GYP file to build the "gm" (golden master) executable.
 {
   'includes': [
     'apptype_console.gypi',
   ],
   'targets': [
     {
       'target_name': 'gm_expectations',
       'type': 'static_library',
       'include_dirs' : [
@@ skipping 55 matching lines @@
           'defines': [
             'SK_BUILD_NATIVE_PDF_RENDERER',
           ],
           'include_dirs' : [
             '../experimental/PdfViewer/inc',
           ],
           'dependencies': [
             'pdfviewer_lib.gyp:pdfviewer_lib',
           ],
         }],
-        ['skia_os in ["linux", "mac", "win"]', {
+        ['skia_poppler_enabled', {
           'dependencies': [
             'poppler.gyp:libpoppler-cpp-gpl',
           ],
           'sources': [
             '../src/utils/SkPDFRasterizer.cpp',
           ],
           'defines': [
             'SK_BUILD_POPPLER',
           ],
         }],
@@ skipping 21 matching lines @@
             '../src/gpu',
           ],
           'dependencies': [
             'gputest.gyp:skgputest',
           ],
         }],
       ],
     },
   ],
 }