Pepper: Remove some gyp defines for trusted plugin.

As far as I can tell, these defines shouldn't have any effect. I'd like to make
the trusted plugin build more similar to what we have for the renderer so that
the transition will be easier when we get rid of the trusted plugin shared
library.

This mirrors a change made to native_client in 2012:
  http://git.chromium.org/gitweb/?p=native_client/src/native_client.git;a=commitdiff;h=c0a9077e3a604521f67f35c9bec3be031dd21465

BUG=394497

Review URL: https://codereview.chromium.org/391343006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@283668 0039d316-1c4b-4281-b951-d872f2087c98

ppapi/native_client/src/trusted/plugin/plugin.gypi

@@ -30,10 +30,6 @@
     },
     'conditions': [
       ['OS=="linux"', {
-        'defines': [
-          'XP_UNIX',
-          'MOZ_X11',
-        ],
         'cflags': [
           '-Wno-long-long',
         ],
@@ -53,13 +49,6 @@
         ],
       }],
       ['OS=="mac"', {
-        'defines': [
-          'XP_MACOSX',
-          'XP_UNIX',
-          'TARGET_API_MAC_CARBON=1',
-          'NO_X11',
-          'USE_SYSTEM_CONSOLE',
-        ],
         'cflags': [
           '-Wno-long-long',
         ],
@@ -74,7 +63,6 @@
       }],
       ['OS=="win"', {
         'defines': [
-          'XP_WIN',
           'WIN32',
           '_WINDOWS'
         ],