libstdc++-v3 script mkcheck problem with multilibs

[Billinghurst, David (CRTS)]

The libstdc++-v3 test script mkcheck has the incorrect relative paths for
multilib target mips-sgi-irix6.5

When testing the -mabi=64 library in directory
mips-sgi-irix6.5/mabi=64/libstdc++-v3 with
	./mkcheck 0 `pwd` /exd4/billingd/src/gcc/libstdc++-v3
the script can find g++

The following changes CXX get things going.   Obviously not the correct fix.

--- mkcheck~    Tue Nov 14 17:16:00 2000
+++ mkcheck     Tue Nov 14 23:00:44 2000
@@ -99,7 +99,7 @@
 # CXX == how to call the compiler
 if [ $WHICH -eq 0 ]; then
   LIB_PATH="$BUILD_DIR/src"
-  CXX="$BUILD_DIR/../../gcc/g++ -B$BUILD_DIR/../../gcc/"
+  CXX="$BUILD_DIR/../../../gcc/g++ -B$BUILD_DIR/../../../gcc/"
 elif [ $WHICH -eq 1 ]; then
   LIB_PATH="$PREFIX_DIR/lib"
   CXX="$PREFIX_DIR/bin/g++"