better support for profiling/feedback optimization/coverage

[Ralf Wildenhues]

Hello automakers,

Luca suggested Automake could be more helpful with profiling,
profile-guided optimization, coverage measurement.

So let's start evaluating the current situation, to get a bit better
overview.  For the packages using C or C++ which I work on, it suffices
to
  ./configure CFLAGS='-fprofile-generate -O2 ...'
  make all check # assuming this will produce typical exercise
  make clean
  ./configure CFLAGS='-fprofile-use -O2 ...'
  make all install

and at least with fairly recent GCC versions, that works in VPATH
builds, too.  Similar for --coverage etc.

So, I guess my question is: do you have more complicated setups or
issues to work around where Automake could help, or where the
information that automake already gets may take away some work from you?
Other good suggestions?

Thanks!
Ralf