Revert "edje: seems like preloading is fixed and we can now run edje_cc in //"

This reverts commit e6a27e13b5.

While preloading itself is fixed, we forgot a little detail there is limit to
the amount of files we can open on any system. This is high enough on Linux that
we never see the issue, but on MacOS X, we can't even build elementary theme.

Reverting this for now and until we have a proper fix for this.

src/bin/edje/edje_cc.c

@@ -38,7 +38,7 @@ int        no_save = 0;
 int        min_quality = 0;
 int        max_quality = 100;
 int        compress_mode = EET_COMPRESSION_HI;
-int        threads = 1;
+int        threads = 0;
 int        annotate = 0;
 int        no_etc1 = 0;
 int        no_etc2 = 0;