Reorganize libjingle path variables.

BUG=chromium:343106
TEST=Trybots passing. I also successfully ran build/gyp_chromium and built Chromium with the talk/build/common.gypi modification in the checkout.
R=andrew@webrtc.org, wu@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/9019004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@5644 4adac7df-926f-26a2-2b94-8c16560cd09d

all.gyp

@@ -7,16 +7,18 @@
 # be found in the AUTHORS file in the root of the source tree.
 
 {
-  'includes': ['talk/build/common.gypi'],
+  'variables': {
+    'libjingle_root%': '<(DEPTH)',
+  },
   'targets': [
     {
       'target_name': 'All',
       'type': 'none',
       'dependencies': [
         'webrtc/webrtc.gyp:*',
-        'talk/libjingle.gyp:*',
-        'talk/libjingle_examples.gyp:*',
-        'talk/libjingle_tests.gyp:*',
+        '<(libjingle_root)/talk/libjingle.gyp:*',
+        '<(libjingle_root)/talk/libjingle_examples.gyp:*',
+        '<(libjingle_root)/talk/libjingle_tests.gyp:*',
       ],
       'conditions': [
         ['OS=="android"', {

talk/build/common.gypi

@@ -46,7 +46,8 @@
   },
   'target_defaults': {
     'include_dirs': [
-      '../..',
+      '<(libjingle_root)',
+      '<(DEPTH)',
       '../../third_party',
       '../../third_party/webrtc',
       '../../webrtc',