pixelflinger: Fix local src arch includes

Automatic handling of LOCAL_SRC_FILES_(ARCH) was introduced in Android
5.0. Lower the SDK version check so these source files don't get
doubly included.

Change-Id: I8ebc7e3e687f2805f6ecb56499cbf39fc31e9545
Reference: see build/core/binary.mk and the handling of my_src_files

libpixelflinger/Android.mk

@@ -96,7 +96,7 @@ LOCAL_SRC_FILES_arm := $(PIXELFLINGER_SRC_FILES_arm)
 LOCAL_SRC_FILES_arm64 := $(PIXELFLINGER_SRC_FILES_arm64)
 LOCAL_SRC_FILES_x86 := $(PIXELFLINGER_SRC_FILES_x86)
 LOCAL_SRC_FILES_mips := $(PIXELFLINGER_SRC_FILES_mips)
-ifneq ($(shell test $(PLATFORM_SDK_VERSION) -gt 22; echo $$?),0)
+ifneq ($(shell test $(PLATFORM_SDK_VERSION) -gt 20; echo $$?),0)
     LOCAL_SRC_FILES += $(LOCAL_SRC_FILES_$(TARGET_ARCH))
 endif
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include