Move cgit_version from shared.c to cgit.c

With the matching Makefile change, this makes sure that only cgit.o and cgit
proper needs to be rebuildt when VERSION has been modified.

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

cgit.c

@@ -10,6 +10,8 @@
 #include "cmd.h"
 #include "ui-shared.h"
 
+const char *cgit_version = CGIT_VERSION;
+
 void config_cb(const char *name, const char *value)
 {
 	if (!strcmp(name, "root-title"))