Adjust ndk-build implementation for old NDK versions

Adjust ndk-build implementation for old NDK versions

* configure.ac: Pass ANDROID_CFLAGS to ndk_INIT.
* cross/ndk-build/Makefile.in (NDK_BUILD_CFLAGS):
* cross/ndk-build/ndk-build-shared-library.mk
($(call objname,$(LOCAL_MODULE),$(basename $(1)))):
($$(error Unsupported suffix):
* cross/ndk-build/ndk-build-static-library.mk
($(call objname,$(LOCAL_MODULE),$(basename $(1)))):
($$(error Unsupported suffix): Use NDK_BUILD_CFLAGS.
* m4/ndk-build.m4 (ndk_INIT): Accept cflags.
(ndk_CONFIG_FILES): Export NDK_BUILD_CFLAGS.