Bug 1412983 - part 4 - make extra_toolchain_flags depend on stlport_cppflags; r=ted.mielczarek

extra_toolchain_flags is used for compiling target-specific bits of code
elsewhere in configure.  Very shortly, we'll need to compile bits of
code that depend on the C++ standard library, so we'll want to point the
compiler at the C++ standard library.  Making extra_toolchain_flags
include stlport_cppflags is the best way to do that.

build/moz.configure/android-ndk.configure

@@ -241,14 +241,16 @@ def stlport_cppflags(value, ndk, _):
 add_old_configure_assignment('stlport_cppflags', stlport_cppflags)
 
 
-@depends(android_platform, android_toolchain)
-def extra_toolchain_flags(platform_dir, toolchain_dir):
+@depends(android_platform, android_toolchain, stlport_cppflags)
+def extra_toolchain_flags(platform_dir, toolchain_dir, stlport_cppflags):
     if not platform_dir:
         return []
-    return ['-isystem',
+    flags = ['-isystem',
              os.path.join(platform_dir, 'usr', 'include'),
              '-gcc-toolchain',
              toolchain_dir]
+    flags.extend(stlport_cppflags if stlport_cppflags else [])
+    return flags
 
 
 @depends(android_toolchain_prefix_base, android_toolchain)