Support to build native libraries with prebuilt NDK

Bug: http://b/issue?id=2811253
Change-Id: Iabd4ab8b3d7236dffe89f1939e1142e882944026
diff --git a/core/config.mk b/core/config.mk
index 2dcd876..20be691 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -315,6 +315,7 @@
 # ###############################################################
 
 HISTORICAL_SDK_VERSIONS_ROOT := $(TOPDIR)prebuilt/sdk
+HISTORICAL_NDK_VERSIONS_ROOT := $(TOPDIR)prebuilt/ndk
 
 # Historical SDK version N is stored in $(HISTORICAL_SDK_VERSIONS_ROOT)/N.
 # The 'current' version is whatever this source tree is.
@@ -336,4 +337,8 @@
     $(patsubst $(HISTORICAL_SDK_VERSIONS_ROOT)/%/android.jar,%, \
     $(wildcard $(HISTORICAL_SDK_VERSIONS_ROOT)/*/android.jar)))
 
+TARGET_AVAILABLE_NDK_VERSIONS := $(call numerically_sort,\
+    $(patsubst $(HISTORICAL_NDK_VERSIONS_ROOT)/android-ndk-r%,%, \
+    $(wildcard $(HISTORICAL_NDK_VERSIONS_ROOT)/android-ndk-r*)))
+
 INTERNAL_PLATFORM_API_FILE := $(TARGET_OUT_COMMON_INTERMEDIATES)/PACKAGING/public_api.xml