[profile-stdlib][patch] Stdlib advisory tool implemetation

[Paolo Carlini]

Hi,

and first congratulations for the excellent progress in this project!

I have a few rather basic comments:
1- Certainly new testcases don't go in 31_*, because those numbers 
correspond to chapters in the Standard, and I don't think this is an ISO 
Standard yet ;) Maybe subdirectory of the existing onew are ok, as we 
are doing for debug-mode. Or, if you want, a separate subdir is ok, but 
with a different name.
2- Are you really, really, sure you have to change the compiler driver? 
First, we are very close to the end of Stage 1, and we have only a few 
days to convince the compiler maintainers that this is an important 
change for 4.4.0, in case should be submitted separately and clearly 
"advertised". Anyway, for debug-mode and parallel-mode we don't do that, 
and, at the very least for consistency, I think we should reconsider 
carefully the option of simply defining macros.
3- Similarly, are you really, really, really, sure you need a separate 
library? For debug-mode, which isn't really trivial, we managed to avoid 
that.
4- Afterwards, there are smaller issues, like I'm seeing many 
non-"uglified" symbols in headers included by the user-code, this is a 
no-no, *everything* (besides the names of functions, classes and 
constants specified in the Standard, of course) must begin by __ or _ + 
Capital (macros included, really there are no exceptions).
5- In general, we never include C headers, always the <c*> versions and 
we qualify with std:: the calls.
6- More important, **make sure** not using anything not in C89 without 
proper configure-time tests checking for the availability of the 
facility on the given target (then, conditionally, it's Ok including, 
e.g., <execinfo.h>)

Huumm... if the above issues are satisfactorily resolved, I think we are 
actually not so far from committing something!

Paolo.