libnl: build static library

android-clat needs a static libnl, so build a static library.  To
avoid building everything twice, build the static library first
and then use LOCAL_WHOLE_STATIC_LIBRARIES to build a shared library.

Also use LOCAL_EXPORT_C_INCLUDE_DIRS to avoid each module that builds
against libnl to have to import its include dir, and remove the
unnecessary LOCAL_MODULE_TAGS.

Change-Id: Ib78e89e916c402787ba3f801bdf8400cbf0d784a
diff --git a/Android.mk b/Android.mk
index b01e375..f407a83 100644
--- a/Android.mk
+++ b/Android.mk
@@ -27,8 +27,15 @@
 	lib/error.c
 
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
+LOCAL_MODULE := libnl
 
-LOCAL_MODULE_TAGS := eng
+include $(BUILD_STATIC_LIBRARY)
+
+include $(CLEAR_VARS)
+
+LOCAL_WHOLE_STATIC_LIBRARIES := libnl
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
 LOCAL_MODULE := libnl
 
 include $(BUILD_SHARED_LIBRARY)