#3 Check return codes everywhere

[Markus Elfring]

Some checks for return codes are missing.

Example:
Please add more error handling for ...
1. ... null pointers from "fmalloc" and "fcalloc" in
string functions
Would it also be safer to use the function "strncat"?

http://cvs.sourceforge.net/viewcvs.py/ferite/ferite/src/ferite_utils.c?rev=1.29&view=markup

2. ... mutex locking

http://cvs.sourceforge.net/viewcvs.py/ferite/ferite/src/ferite_mem_classic.c?rev=1.33&view=markup