[CHERIoT] Allow __cheri_libcall function pointers to decay to normal function pointers.

[resistor]

#16

[v01dXYZ]

I know C++ is stricter with types but do you think the decay is still valid in this language too ? It doesn't seem this patch implements it for C++ (I tested your test case by renaming it to a cpp file).

[resistor]

I know C++ is stricter with types but do you think the decay is still valid in this language too ? It doesn't seem this patch implements it for C++ (I tested your test case by renaming it to a cpp file).

Good catch, thanks. Added a C++ test and fixed it. Unfortunately the C and C++ paths don't seem to coincide here.