Modify how gpu.gyp includes angle.gyp.

Instead of including dependencies on angle.gyp and then removing
them if skia_angle is not true, only include angle.gyp to begin
with skia_angle is true.

This allows gyp_to_android.py to work when run in the Android tree,
where we don't have third_party/externals (since we do only a git
merge, and no gclient sync.

R=djsollen@google.com, robertphillips@google.com, bsalomon@google.com

Author: scroggo@google.com

Review URL: https://codereview.chromium.org/178223015

git-svn-id: http://skia.googlecode.com/svn/trunk@13618 2bbb7eff-a529-9590-31e7-b0007b416f81

gyp/gpu.gyp

@@ -1,3 +1,4 @@
+# GYP for building gpu
 {
   'target_defaults': {
     'conditions': [
@@ -81,7 +82,6 @@
       'type': 'static_library',
       'standalone_static_library': 1,
       'dependencies': [
-        'angle.gyp:*',
         'core.gyp:*',
         'edtaa.gyp:*',
         'utils.gyp:*',
@@ -94,9 +94,6 @@
         '../src/core',
         '../src/gpu',
       ],
-      'export_dependent_settings': [
-        'angle.gyp:*',
-      ],
       'sources': [
         '<@(skgpu_sources)',
         '<@(skgpu_native_gl_sources)',
@@ -208,16 +205,17 @@
             '../src/gpu/gl/GrGLCreateNativeInterface_none.cpp',
           ],
         }],
-        [ 'not skia_angle', {
+        [ 'skia_angle', {
+          'dependencies': [
+            'angle.gyp:*',
+          ],
+          'export_dependent_settings': [
+            'angle.gyp:*',
+          ],
+        }, { # not skia_angle
           'sources!': [
             '<@(skgpu_angle_gl_sources)',
           ],
-          'dependencies!': [
-            'angle.gyp:*',
-          ],
-          'export_dependent_settings!': [
-            'angle.gyp:*',
-          ],
         }],
         [ 'skia_os == "android"', {
           'sources!': [