libgo: use gc's arch names as the default GOARCHs on MIPS
    
    This means that the gc tools and gofrontend agree on the architecture names
    for the 3 MIPS ABIs which should allow a gofrontend compiler to build go.
    
    Reviewed-on: https://go-review.googlesource.com/46153

From-SVN: r249476
diff --git a/libgo/configure.ac b/libgo/configure.ac
index d16547f..bded202 100644
--- a/libgo/configure.ac
+++ b/libgo/configure.ac
@@ -299,9 +299,9 @@
 	[AC_MSG_ERROR([unknown MIPS ABI])
 [mips_abi="n32"]])])])])
     case "$mips_abi" in
-    "o32") GOARCH=mipso32 ;;
-    "n32") GOARCH=mipsn32 ;;
-    "n64") GOARCH=mipsn64 ;;
+    "o32") GOARCH=mips ;;
+    "n32") GOARCH=mips64p32 ;;
+    "n64") GOARCH=mips64 ;;
     "o64") GOARCH=mipso64 ;;
     esac
     case "$mips_abi" in
@@ -315,7 +315,8 @@
         ;;
     esac
     case "${host}" in
-    mips*el)
+    mips*el-*-*)
+        GOARCH="${GOARCH}le"
         ;;
     *)
 	GOARCH_BIGENDIAN=1