Remove invalid uses of -l and -I

LOCAL_LDLIBS should only be used with -l flags for NDK and some host
libraries. Other uses should use LOCAL_SHARED_LIBRARIES.

LOCAL_LDFLAGS should not contain -l entries, they should be in
LOCAL_LDLIBS instead.

LOCAL_CFLAGS should not contain -I entries, those should use
LOCAL_C_INCLUDES instead.

Change-Id: Ic901aa14651572ac682166becd4f0cd86baecc34
diff --git a/libbacktrace/Android.mk b/libbacktrace/Android.mk
index 632b1b6..356ab8b 100644
--- a/libbacktrace/Android.mk
+++ b/libbacktrace/Android.mk
@@ -25,7 +25,9 @@
 
 libbacktrace_common_cppflags := \
 	-std=gnu++11 \
-	-I external/libunwind/include/tdep \
+
+libbacktrace_common_c_includes := \
+	external/libunwind/include/tdep \
 
 # The latest clang (r230699) does not allow SP/PC to be declared in inline asm lists.
 libbacktrace_common_clang_cflags += \