The code is compiling and running fine event with -std=c99 and -pedantic. There's still a lot of Warnings to fix and some of them are quite tricky. I decided to operate differently, I'll now try to sort files by size and fix/clean/rewrite them in this order. Also, I'll try to make one commit per file to make things clean.
memcheck.h: This file contains nothing
watcom.c: Nothing to see here, the code is clean already. Although I wouldn't be surprised if this file ends up deleted because it seems to refers to the Watcom C Compiler.
gmove.h: Aleary clean file. I modified the way the multiple inclusion protection is written. This will be the same for all headers in this code.
fli_glob.h: Not much to modify, but the header didn't had any multiple inclusion protection. The function header was also ugly with too many whitespaces.
profile.h: Not much to fix. Experimenting with coding style regarding header indentation.
_rt_msg.h: Not much to fix.
rt_crc.h: Ordering function prototypes by alphabetical order. Restoring variables names. Multiple Inclusion protection.