compilers: fix broken CompCert support for release flags
compilers: fix broken CompCert support for release flags

This has been broken ever since the original implementation. Due to a
typo, the optimization flag used a zero instead of an uppercase "o",
which the compiler then breaks on during argument parsing because it is
an invalid argument.

Fixes #10267

mesonbuild/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson,pexip/meson,pexip/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson,pexip/meson