Add mips64 and mips64el CPU platforms (#5866)

tools/niminst/buildsh.tmpl

@@ -123,7 +123,15 @@ case $ucpu in
   *power*|*ppc* )
     mycpu="powerpc" ;;
   *mips* )
-    mycpu="mips" ;;
+    mycpu="$("$CC" -dumpmachine | sed 's/-.*//')"
+    case $mycpu in
+      mips|mipsel|mips64|mips64el)
+        ;;
+      *)
+        echo 2>&1 "Error: unknown MIPS target: $mycpu"
+        exit 1
+    esac
+    ;;
   *arm*|*armv6l* )
     mycpu="arm" ;;
   *aarch64* )

tools/niminst/makefile.tmpl

@@ -114,8 +114,11 @@ endif
 ifeq ($(ucpu),ppc)
   mycpu = ppc
 endif
-ifeq ($(ucpu),mips)
-  mycpu = mips
+ifneq (,$(filter $(ucpu), mips mips64))
+  mycpu = $(shell /bin/sh -c '"$(CC)" -dumpmachine | sed "s/-.*//"')
+  ifeq (,$(filter $(mycpu), mips mipsel mips64 mips64el))
+    $(error unknown MIPS target: $(mycpu))
+  endif
 endif
 ifeq ($(ucpu),arm)
   mycpu = arm