https://github.com/telmich/gpm/commit/80cac2a2bd7eed7e80626559f792f37319030729

From: "Desmond O. Chang" <dochang@gmail.com>
Date: Wed, 13 Apr 2016 21:17:48 +0800
Subject: [PATCH] Add gcc include path

Close #13
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -96,7 +96,7 @@ $(DEPFILE) dep: prog/gpm-root.c
 
 	# create dependencies
 	for DEPS in `echo *.c */*.c`; do \
-	$(CC) -I. -I $(srcdir) -M @CPPFLAGS@ $(CPPFLAGS) $$DEPS | \
+	$(CC) -I. -I $(srcdir) -I $(srcdir)/headers -M @CPPFLAGS@ $(CPPFLAGS) $$DEPS | \
 	$(SED) 's/^\(.*\)\.o\([ :]+\)/\1.o \1.lo\2/g' >> $(DEPFILE) ; done
 
 ### INSTALL