#45 Fix mono bindings

[Rosen Penev]

gmcs has been retired for quite a while now. Patch to use mcs:

git diff 10e238fb378a73696c301b524ff751685750b1f3 735eb8ac264db56ae0e3ca920d8691be348a8656
diff --git a/m4/mono.m4 b/m4/mono.m4
index 3603108..3e296a9 100644
--- a/m4/mono.m4
+++ b/m4/mono.m4
@@ -34,7 +34,7 @@ AC_DEFUN([SHAMROCK_FIND_PROGRAM_OR_BAIL],

AC_DEFUN([SHAMROCK_FIND_MONO_2_0_COMPILER],

- SHAMROCK_FIND_PROGRAM_OR_BAIL(MCS, gmcs)
+ SHAMROCK_FIND_PROGRAM_OR_BAIL(MCS, mcs)
)

AC_DEFUN([SHAMROCK_FIND_MONO_RUNTIME],