Merge r61076 from upstream repository.

  ruby/ruby@a4804fb

Author: hsbt

ext/date/prereq.mk

@@ -2,7 +2,7 @@
 
 .list.h:
 	gperf -E -C -c -P -p -j1 -i 1 -g -o -t -N $(*F) $< \
-	| sed 's/(int)(long)&((\(struct stringpool_t\) *\*)0)->\(stringpool_[a-z0-9]*\)/offsetof(\1, \2)/g' \
+	| sed -f $(top_srcdir)/tool/gperf.sed \
 	> $(@F)
 
 zonetab.h: zonetab.list