Use lowercase when computing hashes in hash_getcode()

It turns out hash_findcase() has never worked properly because the correct bucket would never have been searched.

git-svn-id: https://svn.eduke32.com/eduke32@7364 1a8010ca-5511-0410-912e-c29ae57300e0

source/build/include/hash.h

@@ -29,7 +29,7 @@ static inline uint32_t hash_getcode(const char *s)
     uint32_t h = 5381;
     int32_t ch;
 
-    while ((ch = *s++) != '\0')
+    while ((ch = Btolower(*s++)) != '\0')
         h = ((h << 5) + h) ^ ch;
 
     return h;