utils: build sha1/disk cache only with Android/Autoconf

Earlier commit imported a SHA1 implementation and relaxed the SHA1 and
disk cache handling, broking the Windows builds.

Restrict things for now until we get to a proper fix.

Fixes: d1efa09d34 "util: import sha1 implementation from OpenBSD"
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>

src/util/disk_cache.c

@@ -21,6 +21,8 @@
  * IN THE SOFTWARE.
  */
 
+#ifdef ENABLE_SHADER_CACHE
+
 #include <ctype.h>
 #include <string.h>
 #include <stdlib.h>
@@ -705,3 +707,5 @@ disk_cache_has_key(struct disk_cache *cache, cache_key key)
 
    return memcmp(entry, key, CACHE_KEY_SIZE) == 0;
 }
+
+#endif /* ENABLE_SHADER_CACHE */