http://sourceware.org/ml/libffi-discuss/2009/msg00289.html

--- libgomp/configure.ac
+++ libgomp/configure.ac
@@ -110,6 +110,7 @@
 m4_rename([_AC_ARG_VAR_PRECIOUS],[real_PRECIOUS])
 m4_define([_AC_ARG_VAR_PRECIOUS],[])
 AC_PROG_CC
+m4_undefine([_AC_ARG_VAR_PRECIOUS])
 m4_rename([real_PRECIOUS],[_AC_ARG_VAR_PRECIOUS])
 
 AC_SUBST(CFLAGS)