Bug 750574 - Only use "fixed" egrep command on OS X 10.7 [r=ted]

configure.in

@@ -8840,11 +8840,11 @@ xpcom/xpcom-private.h
 
 # Hack around an Apple bug that effects the egrep that comes with OS X 10.7.
 # "arch -arch i386 egrep" always uses the 32-bit Intel part of the egrep fat
-# binary, even on 64-bit systems.  It should work on OS X 10.4.5 and up.  We
-# (apparently) only need this hack when egrep's "pattern" is particularly
-# long (as in the following code).  See bug 655339.
+# binary, even on 64-bit systems. We (apparently) only need this hack when
+# egrep's "pattern" is particularly long (as in the following code).
+# See bug 655339.
 case "$host" in
-*-apple-darwin*)
+*-apple-darwin11*)
     FIXED_EGREP="arch -arch i386 egrep"
     ;;
 *)