Update tests in smg_External_Allocation_Test

Rename tests so instead of weird numeration most files have somewhat meaningful suffixes to help distinguish the variants.

Fix issues when .yml has wrong .c as input Fix function-pointers-* and pointer-* source code so they are compilable.

Remove a duplicate test: undef.c

Simplify some tests, move some variants into separate tests, so there is clearly one violation of one subproperty.

Remove redundant empty lines and update license years too.

Specify 64-bit machine model for err-ptr tests (and update yml format to 2.0); other tests don't seem to need it.

Closes #34