Merge branch 'tb/avoid-gcc-on-darwin-10-6'

Out-of-maintenance gcc on OSX 10.6 fails to compile the code in
'master'; work it around by using clang by default on the platform.

* tb/avoid-gcc-on-darwin-10-6:
  config.mak.uname: use clang for Mac OS X 10.6

Author: gitster

config.mak.uname

@@ -102,6 +102,9 @@ ifeq ($(uname_S),Darwin)
 	ifeq ($(shell expr "$(uname_R)" : '[15]\.'),2)
 		NO_STRLCPY = YesPlease
 	endif
+	ifeq ($(shell test "`expr "$(uname_R)" : '\([0-9][0-9]*\)\.'`" -eq 10 && echo 1),1)
+		CC = clang
+	endif
 	ifeq ($(shell test "`expr "$(uname_R)" : '\([0-9][0-9]*\)\.'`" -ge 11 && echo 1),1)
 		HAVE_GETDELIM = YesPlease
 	endif