[libc][math] Qualify fdim funtions to constexpr (#194137) Signed-off-by: udaykiriti <udaykiriti624@gmail.com> Co-authored-by: Muhammad Bassiouni <60100307+bassiounix@users.noreply.github.com> GitOrigin-RevId: 71816ef062df569c4a0e99204ab79a283bf1dda7