RFC: introduce common.m4

[Tom Tromey]

>>>>> "Pedro" == Pedro Alves <palves@redhat.com> writes:

Pedro> I think you misunderstood the question.

Indeed.  Sorry about that.

>> The rule I propose is that if something is needed or used by common,
>> it should be checked for by common.m4; but that code outside this
>> directory also be free to use these results.  This means that removing
>> checks from common.m4 must first be preceded by looking at uses in gdb
>> and gdbserver.  I think this is pretty easy to do -- easier than what
>> we are doing now -- and I have documented the requirement.

Pedro> over keeping common aware of the checks it needs to do (in common.m4),
Pedro> and gdb/ and gdbserver/ also doing the checks they need for code under
Pedro> gdb/ and gdbserver/ respectively.

Pedro> Of course the current status of needing to update gdb and gdbserver in
Pedro> parallel for common/ things is no good.

Yeah, there is no deep reason for it other than wanting to avoid
duplicate checks.  The cache would work fine for the performance aspect.
I can certainly just drop the configure.ac changes if you think that
yields a better result.

Tom