[plug] overriding default c++ compiler

[Craig Ringer]

> you want 
> export CXX=g++
> or whatever compiler, most C++ things seem to uce 'CXX'
> 
> such as 'CXXFLAGS' another environment variable

Thanks trent, harry. Mozilla won't compile with CXX=g++-3.2 but it is 
using the newer compiler at least. I'm having a go at compiling my _big_ 
  apps (Mozilla, OO.o, Xfree) with gcc3 and mcpu=athlon just to see if 
it works - after all no harm done if it doesn't.