Make sceKernelSetCompiledSdkVersion() available to all tests

This puts the imports in common, since they don't exist in pspsdk by default (at least, not in mine...)

It also:
 * Fixes __testfinish.txt files getting dropped in random places after the host0: hack.
 * Stops the semaphores test from using printf() again (was reverted accidentally I think.)
 * Prints slightly less noise for successful gentest.py runs.
 * Recompiles a bunch of tests with the --sdkver= option.

Ultimately, I did not find many tests with differences, so I think this'll be most useful when spot testing (e.g. by using -a when creating a test, or else just calling the functions within the test.)

-[Unknown]