Bug 1412983 - part 2 - use extra_toolchain_flags for computing bindgen flags; r=ted.mielczarek

We compute the same set of data in extra_toolchain_flags as we were
computing in bindgen_cflags_defaults.  We might as well reuse the former
to compute the latter.

build/moz.configure/android-ndk.configure

@@ -260,11 +260,11 @@ def stlport_cppflags(value, ndk, _):
 add_old_configure_assignment('stlport_cppflags', stlport_cppflags)
 
 
-@depends(stlport_cppflags, android_platform, android_toolchain,
+@depends(stlport_cppflags, extra_toolchain_flags, android_toolchain,
          android_toolchain_prefix_base, '--help')
 @imports(_from='os.path', _import='isdir')
-def bindgen_cflags_defaults(stlport_cppflags, android_platform, toolchain,
-                            toolchain_prefix, _):
+def bindgen_cflags_defaults(stlport_cppflags, toolchain_flags,
+                            toolchain, toolchain_prefix, _):
     if not stlport_cppflags:
         return
 
@@ -274,10 +274,9 @@ def bindgen_cflags_defaults(stlport_cppflags, android_platform, toolchain,
         gcc_include = os.path.join(
             toolchain, 'lib', 'gcc', toolchain_prefix, '4.9')
 
-    cflags_format = "%s -isystem %s -gcc-toolchain %s -I%s -I%s"
+    cflags_format = "%s %s -I%s -I%s"
     return cflags_format % (' '.join(stlport_cppflags),
-                            os.path.join(android_platform, 'usr', 'include'),
-                            toolchain,
+                            ' '.join(toolchain_flags),
                             os.path.join(gcc_include, 'include'),
                             os.path.join(gcc_include, 'include-fixed'))