[RDY] Fix clang analysis warnings. (2)

This continues the work in #1389.

Fixed **17** warnings in:
- ex_cmds.c.
- ex_cmds2.c
- ex_docmd.c
- ex_eval.c
- ex_getln.c
- fileio.c
- fold.c
- hardcopy.c
- memory.c
- message.c