Use += for both assignments to LOCAL_C_INCLUDES

include_dirs and local_include_dirs properties both translate to
LOCAL_C_INCLUDES.  Use += for both assignments so they don't
clobber eachother.

Change-Id: Ie9e5e28ecd5a7ca76ab2a981e7d50d2c9b93ad92
diff --git a/androidbp/cmd/soong.go b/androidbp/cmd/soong.go
index ff026a4..ecae5b0 100644
--- a/androidbp/cmd/soong.go
+++ b/androidbp/cmd/soong.go
@@ -27,7 +27,6 @@
 	"static_libs":        {"LOCAL_STATIC_LIBRARIES", bpparser.List},
 	"whole_static_libs":  {"LOCAL_WHOLE_STATIC_LIBRARIES", bpparser.List},
 	"system_shared_libs": {"LOCAL_SYSTEM_SHARED_LIBRARIES", bpparser.List},
-	"include_dirs":       {"LOCAL_C_INCLUDES", bpparser.List},
 	"asflags":            {"LOCAL_ASFLAGS", bpparser.List},
 	"clang_asflags":      {"LOCAL_CLANG_ASFLAGS", bpparser.List},
 	"cflags":             {"LOCAL_CFLAGS", bpparser.List},
@@ -66,6 +65,7 @@
 	string
 	f func(name string, prop *bpparser.Property, suffix *string) ([]string, error)
 }{
+	"include_dirs":        {"LOCAL_C_INCLUDES", appendAssign},
 	"local_include_dirs":  {"LOCAL_C_INCLUDES", prependLocalPath},
 	"export_include_dirs": {"LOCAL_EXPORT_C_INCLUDE_DIRS", prependLocalPath},
 	"suffix":              {"LOCAL_MODULE_STEM", prependLocalModule},