Fixed a quoting error.

scripts/xenofarm.sh

@@ -137,7 +137,7 @@ makewarn () {
     # as of 2003-07-16.
     if grep '/i/gcc/2\.95\.2/lib/gcc-lib/hppa1\.1-hp-hpux11\.00/2\.95\.2/include/stddef\.h:165: warning: this is the location of the previous definition' r/makewarn.txt >/dev/null 2>&1
     then
-	grep -v 'warning: `/usr/include/.*__size_t' redefined' r/makewarn.txt \
+	grep -v 'warning: `/usr/include/.*__size_t. redefined' r/makewarn.txt \
 	| grep -v '2\.95\.2/include/stddef.h:165: warning: this is the' \
 	| grep -v '/i/gcc/.*/string\.h:.*conflicting types for built-in func' \
 	> r/makewarn2.txt