Update .gitmodules to point to the actual libgit2 host now.

Author: andreberg

.gitmodules

@@ -1,7 +1,3 @@
 [submodule "libgit2"]
     path = libgit2
-    url = git://github.com/pieter/libgit2.git
-
-# Please don't change the submodule link since we really need the
-# "saved" libgit2 from Pieter's repo as GitX uses a deprecated function 
-# to calculate the realSha
+    url = git://repo.or.cz/libgit2.git