Have Makefile import local.mk if it exists.

This will allow users to override build settings without dirtying their
trees, making life with `git stash' a bit easier.

Signed-off-by: Samuel Bronson <naesten@gmail.com>
Signed-off-by: Christopher Li <sparse@chrisli.org>

.gitignore

@@ -33,3 +33,7 @@ patches-*
 # quilt's files
 patches
 series
+
+# local makefile
+local.mk
+

Makefile

@@ -10,9 +10,10 @@ LDFLAGS += -g
 AR = ar
 
 #
-# For debugging, uncomment the next one
+# For debugging, put this in local.mk:
+#
+#     CFLAGS += -O0 -DDEBUG -g3 -gdwarf-2
 #
-#CFLAGS += -O0 -DDEBUG -g3 -gdwarf-2
 
 HAVE_LIBXML=$(shell pkg-config --exists libxml-2.0 && echo 'yes')
 HAVE_GCC_DEP=$(shell touch .gcc-test.c && 				\
@@ -89,6 +90,11 @@ SED_PC_CMD = 's|@version@|$(VERSION)|g;		\
 	      s|@includedir@|$(INCLUDEDIR)|g'
 
 
+
+# Allow users to override build settings without dirtying their trees
+-include local.mk
+
+
 all: $(PROGRAMS) sparse.pc
 
 install: $(INST_PROGRAMS) $(LIBS) $(LIB_H) sparse.pc