work around dejagnu bug causing spurious failures

[Jeffrey A Law]

  In message < 20000403160306.M792@wolery.cumb.org >you write:
  > A number of the cpp tests are failing spuriously because of a bug in
  > dejagnu.  The new preprocessor issues error messages with column
  > numbers.  That can confuse the error-matching regexp in dg.exp, causing
  > it to match lines it shouldn't, which are then unavailable to be
  > matched by other tests.
  > 
  > This patch works around the bug, by disabling column numbers in all
  > the test cases where it makes a difference.  The changes to the specs
  > are necessary so that the driver propagates -fno-show-column to the
  > preprocessor.
  > 
  > zw
  > 
  > 	* gcc.c (C specs): Pass -f(no-)show-column to the
  >           preprocessor.
  > 	* ch/lang-specs.h, cp/lang-specs.h, f/lang-specs.h,
  > 	objc/lang-specs.h: Likewise.
  > 
  > 	* gcc.dg/cpp-redef-2.c, gcc.dg/cpp-tradwarn1.c,
  > 	gcc.dg/cpp-unc.c: Add -fno-show-column to compiler options.
I'd rather see us fix the testsuite driver to handle column numbers than
add a new option to the compiler just to make the testsuite happy.

jeff