not enabled by default

ext/mime_magic/config.m4

@@ -4,7 +4,7 @@ dnl config.m4 for extension mime_magic
 PHP_ARG_ENABLE(mime_magic, whether to enable mime_magic support,
 [  --enable-mime_magic           Enable mime_magic support])
 
-if test "$PHP_MIME_MAGIC" != "no"; then
+if test "$PHP_MIME_MAGIC" = "yes"; then
   dnl PHP_SUBST(MIME_MAGIC_SHARED_LIBADD)
 
   PHP_NEW_EXTENSION(mime_magic, mime_magic.c, $ext_shared)