Include cgit.conf in Makefile

This allows persistent overrides of Makefile settings without touching
the Makefile.

Suggested in a patch by Kristian Høgsberg <krh@bitplanet.net>

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

Makefile

@@ -7,6 +7,11 @@ CACHE_ROOT = /var/cache/cgit
 CGIT_CONFIG = /etc/cgitrc
 CGIT_SCRIPT_NAME = cgit.cgi
 
+#
+# Let the user override the above settings.
+#
+-include cgit.conf
+
 EXTLIBS = git/libgit.a git/xdiff/lib.a -lz -lcrypto
 OBJECTS = shared.o cache.o parsing.o html.o ui-shared.o ui-repolist.o \
 	ui-summary.o ui-log.o ui-view.o ui-tree.o ui-commit.o ui-diff.o \