Make cgit honor CACHE_ROOT as defined in Makefile

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

Makefile

@@ -33,6 +33,7 @@ CFLAGS += -DSHA1_HEADER='$(SHA1_HEADER)'
 CFLAGS += -DCGIT_VERSION='"$(CGIT_VERSION)"'
 CFLAGS += -DCGIT_CONFIG='"$(CGIT_CONFIG)"'
 CFLAGS += -DCGIT_SCRIPT_NAME='"$(CGIT_SCRIPT_NAME)"'
+CFLAGS += -DCGIT_CACHE_ROOT='"$(CACHE_ROOT)"'
 
 
 cgit: cgit.c $(OBJECTS)