OpenBSD needs the strcasestr replacement.

Noticed by Randal L. Schwartz.

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/Makefile b/Makefile
index b8ca504..e67d0e7 100644
--- a/Makefile
+++ b/Makefile
@@ -180,6 +180,7 @@
 	ARM_SHA1 = YesPlease
 endif
 ifeq ($(shell uname -s),OpenBSD)
+	NO_STRCASESTR = YesPlease
 	NEEDS_LIBICONV = YesPlease
 	PLATFORM_DEFINES += -I/usr/local/include -L/usr/local/lib
 endif