[libvirt] [PATCH] maint: show which compiler warning triggered

[Jim Meyering]

Eric Blake wrote:
> * acinclude.m4 (LIBVIRT_COMPILE_WARNINGS): Add
> -fdiagnostics-show-option.
> ---
>
> Here's an example of how things change, when using './configure
> --enable-compiler-warnings=error' and introducing something gcc
> would warn about:
>
>   CC     libvirt_driver_nwfilter_la-nwfilter_ebiptables_driver.lo
> cc1: warnings being treated as errors
> nwfilter/nwfilter_ebiptables_driver.c: In function '_iptablesCreateRuleInstance':
> nwfilter/nwfilter_ebiptables_driver.c:1059: error: unused variable 'oops' [-Wunused-variable]

Looks fine to me.
Thanks for splitting the long line and fixing the m4 quoting, too.