[PATCH v2, testsuite]: Add dg-error for unsupported floating suffix

[Jakub Jelinek]

On Thu, Nov 15, 2012 at 05:31:42PM +0100, Uros Bizjak wrote:
> No, the intention of this test is to check if target can handle these
> suffixes through TARGET_C_MODE_FOR_SUFFIX. Please note that in
> particular tests, -std=x compile switches are added to compile flags.

But -std=c++11 (well, perhaps -std=gnu++11) could be eventually the default.
As Q/W suffixes are only supported in certain modes through
TARGET_C_MODE_FOR_SUFFIX, it is better to put the explicit option that
allows it on the command line of the check_effective_target* test.

	Jakub