Move GNSS_CFLAGS to build/ to be fully included

GNSS_CFLAGS included in pla module cannot be included by all the
modules. Define it in build/target_specific_features.mk to make it
included by the whole project.

Change-Id: Ib13c43a65ecd14a7a97050dd80b4dce6aa8ad339
CRs-fixed: 2168176
diff --git a/Android.mk b/Android.mk
index e2c5a56..23b2a66 100644
--- a/Android.mk
+++ b/Android.mk
@@ -1,5 +1,6 @@
 ifneq ($(BOARD_VENDOR_QCOM_GPS_LOC_API_HARDWARE),)
 LOCAL_PATH := $(call my-dir)
+include $(LOCAL_PATH)/build/target_specific_features.mk
 
 include $(call all-makefiles-under,$(LOCAL_PATH))
 endif