[Bug middle-end/78809] Inline strcmp with small constant strings

[qing.zhao at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78809

--- Comment #33 from Qing Zhao <qing.zhao at oracle dot com> ---
with SPEC2017 on X86, I didn't see any run-time performance change as expected.
due to the date I collected for code size change, looks like that n=3 or n=4
might be a reasonable default. n=3 might be safer.