Backport #2513: CC is ignored in ext
http://redmine.ruby-lang.org/issues/show/2513
e$B5/I<<Te(B: Nobuyoshi N.
e$B%9%F!<%?%9e(B: Open, e$BM%@hEYe(B: Normal
e$BC4Ev<Te(B: Shyouhei U., e$B%+%F%4%je(B: build
configuree$B$KEO$5$l$?e(BCCe$B$,e(Bexte$B0J2<$N%3%s%Q%$%k$G;HMQ$5$l$F$$$^$;$s!#e(B
1.9,1.8e$B$H$b$Ke(Br26005e$B$G=$@5$7$F$"$j$^$9!#e(B