[Patch] Remove some unused checks from configure.

[Andrew Haley]

David Daney writes:
 > Inspired by Tom Tromey's recent post to gcc@, I did a little grepping 
 > and found some unused configure checks.  Removing these significantly 
 > reduces GCC bootstrap times (usually be a second or more) :-).
 > 
 > Tested on x86_64-pc-linux-gnu with no regressions.
 > 
 > OK to commit?

Please don't post generated files in patches -- that's like posting
object files.  Just post the sources.

Thanks,
Andrew.