Fixes #FS-5259 (Thanks to Nathan Neulinger for the patch)

FS5202.

Without setting errmsg to NULL here, we'll try to print this freed
value again below if another error doesn't intercede.

Not that it really matters since we're returning to the OS momentarily
at that point anyway.

  fsg_search.c:263:2: error: non-void function 'fsg_search_reinit' should return a value [-Wreturn-type]

clang:

  error: explicitly assigning a variable of type 'uint16_t' (aka 'unsigned short') to itself [-Werror,-Wself-assign]

Unused variables break the build with recent versions of gcc and
clang.

Disregard the supplemental commit text on
commit a744b202.

switch_util_quote_shell_arg() is fine.

Note that the function switch_util_quote_shell_arg is implemented
incorrectly for unix shells, so this is still not safe until that
function is fixed.
Reported-by: Nathan Neulinger <nneul@mst.edu>

FS-5450 --resolve

We were using both switch_util_quote_shell_arg and
switch_string_replace without freeing the results even though both
functions malloc.

Thanks-to: Nathan Neulinger <nneul@mst.edu>

FS-5448 --resolve

Thanks-to: Mariusz Czułada <manieq.net@gmail.com>

Thanks-to: Alexandre Snarskii <snar@snar.spb.ru>

FS-5465 --resolve

FS-5472 --resolve

This fixes the build on gcc-4.7.3.  The build was breaking with:

  error: ignoring return value of 'strerror_r', declared with attribute warn_unused_result [-Werror=unused-result]

It's been missing a break there for ~4 years and instead using the 8k max_ms values(the ptime_div value is the same).