Re: [libvirt] [PATCH] build: use more gnulib modules for simpler code

* .gnulib: Update to latest, for sigpipe and sigaction modules. * bootstrap.conf (gnulib_modules): Add siaction, sigpipe, strerror_r. * tools/virsh.c (vshSetupSignals) [!SIGPIPE]: Delete, now that gnulib guarantees it. (SA_SIGINFO): Define for mingw fallback. * src/util/virterror.c (virStrerror): Simplify, now that gnulib guarantees the POSIX interface. * configure.ac (AC_CHECK_FUNCS_ONCE): Drop redundant check. (AM_PROG_CC_STDC): Move earlier, to keep autoconf happy. --- Gnulib makes it possible to prefer the POSIX strerror_r signature everywhere, even on Linux.  And even though mingw lacks SA_SIGINFO (even with gnulib), the virsh signal handler still works for mingw with gnulib's implementation of SIGPIPE with minimal effort.