Add support for the OpenBSD for Bitrig.

Patch by David Hill.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161344 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/autoconf/ltmain.sh b/autoconf/ltmain.sh
index 2455278..21ace01 100644
--- a/autoconf/ltmain.sh
+++ b/autoconf/ltmain.sh
@@ -1560,7 +1560,7 @@
 	    # These systems don't actually have a C library (as such)
 	    test "X$arg" = "X-lc" && continue
 	    ;;
-	  *-*-openbsd* | *-*-freebsd* | *-*-dragonfly*)
+	  *-*-openbsd* | *-*-freebsd* | *-*-dragonfly* | *-*-bitrig*)
 	    # Do not include libc due to us having libc/libc_r.
 	    test "X$arg" = "X-lc" && continue
 	    ;;
@@ -1580,7 +1580,7 @@
 	  esac
 	elif test "X$arg" = "X-lc_r"; then
 	 case $host in
-	 *-*-openbsd* | *-*-freebsd* | *-*-dragonfly*)
+	 *-*-openbsd* | *-*-freebsd* | *-*-dragonfly* | -*-*-bitrig*)
 	   # Do not include libc_r directly, use -pthread flag.
 	   continue
 	   ;;
@@ -3464,7 +3464,7 @@
 	  *-*-netbsd*)
 	    # Don't link with libc until the a.out ld.so is fixed.
 	    ;;
-	  *-*-openbsd* | *-*-freebsd* | *-*-dragonfly*)
+	  *-*-openbsd* | *-*-freebsd* | *-*-dragonfly* | *-*-bitrig*)
 	    # Do not include libc due to us having libc/libc_r.
 	    ;;
 	  *-*-sco3.2v5* | *-*-sco5v6*)