This makes the point where execution starts more obvious compared to a start_of_test label at the end of the include, and allows putting other functions at the start of the file. This change also modifies the existing tests to build with this change.
`IsLess` would incorrectly return true if both `SR_OVERFLOW` and `SR_SIGN` are set, as `(sr & SR_OVERFLOW) != (sr & SR_SIGN)` becomes `SR_OVERFLOW != SR_SIGN` which is true as the two masks are different. This broke in e651592ef5.
This issue only affected the DSP LLE Interpreter, and not the DSP LLE JIT.
I've also included a simple test case for this. `ax0.l` (on the top left) is set to 0 if the instruction following `IFL` does not execute and to 1 if it is executed.
