Merge pull request #39 from unknownbrackets/ge-callbacks

Add some tests for jump/call/ret signals
Add makefiles and compile a few gpu tests.
Add some tests for Dcache errors.

So we can safely ignore anything the PSP ignores, for sure.
No need for libc to be in a subdir now.
Merge pull request #40 from unknownbrackets/dcache

Dcache tests
No need for this call, was just adding confusion.

It fails anyway inside a signal handler (need to test what all does.)