lib: fix warnings in fallback set_time logic

Fix the build time warnings:

safe_file_ops.c: In function 'safe_touch':
safe_file_ops.c:237:4: warning: passing argument 2 of 'set_time' discards 'const' qualifier from pointer target type [enabled by default]
safe_file_ops.c:165:13: note: expected 'struct timespec *' but argument is of type 'const struct timespec *'
safe_file_ops.c:239:4: warning: passing argument 2 of 'set_time' discards 'const' qualifier from pointer target type [enabled by default]
safe_file_ops.c:165:13: note: expected 'struct timespec *' but argument is of type 'const struct timespec *'

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
lib: tests: fix up build time warnings

The variable "unused" triggered a warning because it was unused.
Workaround the compile time warning about not checking write's
return value in a different way.

The argc arg was warned about being unused, so label it.

Check the system() return value explicitly.

Also clean up whitespace.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
lib: fix noreturn warnings

We know this code will never return, but gcc does not.
Add an explicit abort() to avoid gcc warning about it.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>