Remove the TCC loader

We got this mostly working using https://github.com/frida/tinycc as a
subproject, but TCC doesn't find glib and there's no way to tell it to search
pkg-config, so we're basically at a stand still until something changes there.

So rather than leaving this sitting around forever, we're going to prune it
for now, and we can always revisit this commit later or rebuild it as it's not
super complicated.

Testing Done:
Compiled and ran `ninja gplugin-pot`.

Reviewed at https://reviews.imfreedom.org/r/1910/