Get gpudft support working in dm, gm, nanobench and bench_pictures

Adds a new config to test distance field text.
Clean up some flags and #defines to read "distance field text",
not "distance field fonts" to be consistent with Chromium

NOTREECHECKS=true

Committed: https://skia.googlesource.com/skia/+/06ba179838ba4fe187cf290750aeeb4a02a2960b

Review URL: https://codereview.chromium.org/699453005
diff --git a/gyp/common_variables.gypi b/gyp/common_variables.gypi
index ab25eef..09d84ec 100644
--- a/gyp/common_variables.gypi
+++ b/gyp/common_variables.gypi
@@ -152,7 +152,7 @@
       'skia_win_debuggers_path%': '',
       'skia_shared_lib%': 0,
       'skia_opencl%': 0,
-      'skia_force_distancefield_fonts%': 0,
+      'skia_force_distance_field_text%': 0,
 
       # These variables determine the default optimization level for different
       # compilers.
@@ -231,7 +231,7 @@
     'skia_profile_enabled%': '<(skia_profile_enabled)',
     'skia_shared_lib%': '<(skia_shared_lib)',
     'skia_opencl%': '<(skia_opencl)',
-    'skia_force_distancefield_fonts%': '<(skia_force_distancefield_fonts)',
+    'skia_force_distance_field_text%': '<(skia_force_distance_field_text)',
     'skia_static_initializers%': '<(skia_static_initializers)',
     'ios_sdk_version%': '6.0',
     'skia_win_debuggers_path%': '<(skia_win_debuggers_path)',