#1698 PIC16: string functions not const-correct

[Christopher Head]

In include/pic16/string.h, all the prototypes are non-const-correct. Things like memcpy, strcpy, strlen, and many others take non-const source parameters in their prototypes. This is in v3.0.0. There was even bug #1568836 about fixing const-correctness in memcpypgm2ram, but that only fixed const correctness in a local variable used in the function, not in the parameter types.

[Philipp Klaus Krause]

Why does the pic16 port need it's own string.h anyway? Even if it wants to provide those extra functions like memcpypgm2ram, it should just include our standard string.h for the standard functions in the port-specific string.h.
That would ease maintenance and fix this bug.

Philipp