Specify parameters for all C functions. Not specifying parameters is the
same as specifying "void" in C++ and in C23 and later but that's not the
case in C prior to C23.
Compile C files with the same warnings as C++ files, additionally making
the strict prototypes warning an error to catch such problems in the
future. This commit isn't intended to address all the other warnings now
being emitted.
Ryan Schmidt
Wolfgang Thaller