Add the capability to specify JIT options on the SPMI command line.

Add the capability to specify JIT options on the SPMI command line.

This change adds two new flags, `-jitoption` and `-jit2option`, to the
SuperPMI command line. These flags are cumulative, and are used to
specify JIT config options (e.g. `COMPlus_JitDisasm`, albeit without the
`COMPlus_` prefix) to the base and diff JITs, respectively.

This change also removes Smarty-specific code and support for capturing
and replaying environment variables. The former is no longer terribly
useful and the latter has been obviated by the JIT host interface.