[ccache] configuring more than one compiler for ccache

[Diane Cronin]

Ok I have now learned that I can override the defaults to the configure 
script. Setting CC to be the c++ compiler (currently working on tru64 
and using cxx) goes through. However when running the compiles I get 
"failed to rename tmp files - No such file or directory" written to the 
cache log - any ideas on how to proceed?