* Don't try to generate C header files yet since it will only cause a
crash saying the feature is unimplemented.
* Rename the CLI options for release modes to use the `-O` prefix to
match C compiler precedent. Options are now `-ODebug`,
`-OReleaseFast`, `-OReleaseSafe`, `-OReleaseSmall`. The optimization
mode matches the enum tags of std.builtin.Mode. It is planned to, at
some point, rename std.builtin.Mode to std.builtin.OptimizationMode
and modify the tags to be lower case to match the style convention.
- Update build.zig code to support this new CLI.
* update std.zig.binNameAlloc to support an optional Version and update
the implementation to correctly deal with dynamic library version
suffixes.