3.2.3 patch for Xtensa - remove poisoned macros

[Gabriel Dos Reis]

Bob Wilson <bwilson@tensilica.com> writes:

| I was just informed that the Xtensa port on the 3.2 branch can only be built 
| as a cross compiler because it defines several macros that have been 
| poisoned.  The attached patch fixes this by removing the poisoned macro 
| definitions.  This seems to fit the criteria for last-minute 3.2.3 patches: 
| it's essentially zero risk and without it you can't build a native Xtensa 
| compiler.

OK.

-- Gaby