change default build (in "make" wrapper) to ninja on all platforms

gyp/common_conditions.gypi

Index: gyp/common_conditions.gypi
diff --git a/gyp/common_conditions.gypi b/gyp/common_conditions.gypi
index 82f63f375bf15e92013bcc8a2338093412798012..70effa17239f56e89f0bccc973b8f6e8991e1b5f 100644
--- a/gyp/common_conditions.gypi
+++ b/gyp/common_conditions.gypi
@@ -85,6 +85,22 @@
               },
             },
           },
+          # Gyp's ninja generator depends on these specially named
+          # configurations to build 64-bit on Windows.
+          # See http://skbug.com/2348
+          #
+          # We handle the 64- vs 32-bit variations elsewhere, so I think it's
+          # OK for us to just make these inherit non-archwidth-specific
+          # configurations without modification.
+          'Debug_x64': {
+            'inherit_from': ['Debug'],
+          },
+          'Release_x64': {
+            'inherit_from': ['Release'],
+          },
+          'Release_Developer_x64': {
+            'inherit_from': ['Release_Developer'],
+          },
         },
         'conditions' : [
           [ 'skia_arch_width == 64', {