Fix driver/33980: Precompiled header file not removed on error

Fix driver/33980: Precompiled header file not removed on error

So the problem here is that in the spec files, we were not marking the pch
output file to be removed on error.
The way to fix this is to mark the --output-pch argument as the output
file argument.
For the C++ specs file, we had to move around where the %V was located
such that it would be after the %w marker as %V marker clears the outputfiles.

OK? Bootstrapped and tested on x86_64-linux-gnu.

gcc/cp/ChangeLog:

	PR driver/33980
	* lang-specs.h ("@c++-header"): Add %w after
	the --output-pch.
	("@c++-system-header"): Likewise.
	("@c++-user-header"): Likewise.

gcc/ChangeLog:

	PR driver/33980
	* gcc.cc (default_compilers["@c-header"]): Add %w
	after the --output-pch.