Comment 161 for bug 233901

(In reply to comment #10)
> no,
> in fact I use rpmbuild , which read a firefox.spec and automatically untar,
> patch, compile, and create an rpm package.
> the build section in the firefox.spec file contains:
> %build
>
> export RPM_OPT_FLAGS=`echo $RPM_OPT_FLAGS | %{__sed} s/-O2/-Os/`
> MAKE="gmake %{?_smp_mflags}" make -f client.mk build
>
> Indeed I don't see any autoconf nor ./configure in here !

That make command eventually causes configure to run. However, it does not cause autoconf to regenerate configure from configure.in, which would be necessary for the fix you propose to work. As a workaround, try patching configure directly instead of patching configure.in.