[Bug target/87522] LTO incorrectly merges target specific options

[thiago at kde dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87522

--- Comment #2 from Thiago Macieira <thiago at kde dot org> ---
In the original case, all sources were compiled with -march=westmere, though
some files had -mavx added.