In an MSVC context, `-MT` means
"Use static run-time"
and it is a flag with no parameter.
On POSIX it means
"Specify name of main file output in depfile"
and it is "joined or separate".
The former was interfering with the latter. Now, the MT flag is required
to be specified with a `/` to disambiguate: `/MT`.
* The generated options data file is sorted now in a way that
makes sure longer prefixes are first. This prevents collisions
with some parameters.
* Add support for `-fPIC`, `-fno-PIC`, `-nostdlib`, `-shared`,
`-rdynamic`, `-Wl,-soname`, `-Wl,-rpath`
* Better support for `-o`.
* Disable generating h files
* Shared library support.
* Better positional argument support.
Andrew Kelley