android: Remove/filter header files from LOCAL_SRC_FILES

This avoids huge warnings when building the native code.

src/libhydra/Android.mk

@@ -2,7 +2,7 @@ LOCAL_PATH := $(call my-dir)
 include $(CLEAR_VARS)
 
 # copy-n-paste from Makefile.am
-LOCAL_SRC_FILES := \
+libhydra_la_SOURCES := \
 hydra.c hydra.h \
 attributes/attributes.c attributes/attributes.h \
 attributes/attribute_provider.h attributes/attribute_handler.h \
@@ -13,6 +13,8 @@ kernel/kernel_ipsec.c kernel/kernel_ipsec.h \
 kernel/kernel_net.c kernel/kernel_net.h \
 kernel/kernel_listener.h
 
+LOCAL_SRC_FILES := $(filter %.c,$(libhydra_la_SOURCES))
+
 # adding the plugin source files
 
 LOCAL_SRC_FILES += $(call add_plugin, attr)