build system: LTO detection fails if -flto=auto or similar is used

[Tatsh]

Your LTO detection doesn't account for when -flto=auto, -flto=N, etc are used. The arguments are beneficial to tweak LTO processing.

https://github.com/brummer10/guitarix/blob/master/trunk/waftools/cpu_optimization.py#L171-L173

Instead of this check you could use if any(x.startswith('-flto') for x in cxxflags):.

https://bugs.gentoo.org/926429

[brummer10]

Thanks for the pointer. I've pushed the fix to the repository.

[Tatsh]

Thanks!