Allow google dialer code to be compiled against M and N SDKs

+ Defaulted src-N to source directory in makefile

Bug:26330692
Change-Id: Ia78449876539f7a6bdd2f072eaf942c07915640b
diff --git a/Android.mk b/Android.mk
index 47648db..20f3944 100644
--- a/Android.mk
+++ b/Android.mk
@@ -23,6 +23,12 @@
     $(contacts_common_dir)/res \
     $(phone_common_dir)/res
 
+src_dirs += \
+    src-N \
+    $(incallui_dir)/src-N \
+    $(contacts_common_dir)/src-N \
+    $(phone_common_dir)/src-N
+
 LOCAL_SRC_FILES := $(call all-java-files-under, $(src_dirs))
 LOCAL_RESOURCE_DIR := $(addprefix $(LOCAL_PATH)/, $(res_dirs)) \
     $(support_library_root_dir)/v7/cardview/res \