Decouple platform compiler and NDK library versioning.

TARGET_GCC_VERSION: select compiler from prebuilts/gcc/...
TARGET_NDK_GCC_VERSION: select libraries from prebuilts/ndk/...

Change-Id: I4422a42cdc97aa92b40798014cba82c3c123bbd2
diff --git a/core/binary.mk b/core/binary.mk
index cc8de46..13659f5 100644
--- a/core/binary.mk
+++ b/core/binary.mk
@@ -60,9 +60,9 @@
     my_ndk_stl_cppflags := -std=c++11
   else
     # LOCAL_NDK_STL_VARIANT is gnustl_static
-    my_ndk_stl_include_path := $(my_ndk_source_root)/cxx-stl/gnu-libstdc++/$($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_GCC_VERSION)/libs/$(TARGET_$(LOCAL_2ND_ARCH_VAR_PREFIX)CPU_ABI)/include \
-                               $(my_ndk_source_root)/cxx-stl/gnu-libstdc++/$($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_GCC_VERSION)/include
-    my_ndk_stl_static_lib := $(my_ndk_source_root)/cxx-stl/gnu-libstdc++/$($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_GCC_VERSION)/libs/$(TARGET_$(LOCAL_2ND_ARCH_VAR_PREFIX)CPU_ABI)/libgnustl_static.a
+    my_ndk_stl_include_path := $(my_ndk_source_root)/cxx-stl/gnu-libstdc++/$($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_NDK_GCC_VERSION)/libs/$(TARGET_$(LOCAL_2ND_ARCH_VAR_PREFIX)CPU_ABI)/include \
+                               $(my_ndk_source_root)/cxx-stl/gnu-libstdc++/$($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_NDK_GCC_VERSION)/include
+    my_ndk_stl_static_lib := $(my_ndk_source_root)/cxx-stl/gnu-libstdc++/$($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_NDK_GCC_VERSION)/libs/$(TARGET_$(LOCAL_2ND_ARCH_VAR_PREFIX)CPU_ABI)/libgnustl_static.a
   endif
   endif
   endif