[warning control] New #pragma GCC diagnostic

[Gabriel Dos Reis]

DJ Delorie <dj@redhat.com> writes:

| > Assuming, you would work with me to resolve the rest of the issue,
| > i.e. incremental improvements, it is OK.
| 
| I just did an update and started a bootstrap, I'll commit the so-far
| in the morning.  I think the list of follow-ups is:
| 
| * Have -Werror act like a -Werror=* wildcard.
| 
| * Have -Werror-implicit-function-declaration become
|   -Werror=implicit-function-declaration
| 
| * Move option_enabled() logic into the classification array.
| 
| * Somehow hook libcpp into all this.
| 
| * expand for DK_INFO, DK_FATAL, etc.  error() -> DK_FATAL might be
|   useful, letting you immediately halt compilation for *specified*
|   errors.
| 
| * Further out, make the #pragma have finer control (per function or
|   per line, rather than per compilation)

I believe we have a deal.

-- Gaby