adding support for bitrig

(cherry picked from commit 970fcfb)

Conflicts:
	configure.ac

Author: Dave Huseby

configure.ac

@@ -288,6 +288,11 @@ case "${host}" in
 	abi="elf"
 	AC_DEFINE([JEMALLOC_PURGE_MADVISE_FREE], [ ])
 	;;
+  *-*-openbsd*|*-*-bitrig*)
+	CFLAGS="$CFLAGS"
+	abi="elf"
+	AC_DEFINE([JEMALLOC_PURGE_MADVISE_FREE], [ ])
+	;;
   *-*-linux*)
 	CFLAGS="$CFLAGS"
 	CPPFLAGS="$CPPFLAGS -D_GNU_SOURCE"