Get rid of gettext.h
Remove gettext.h from Makefile.am
Fix length of program_argstring in main.c
Replaced xfree_null() by xfree() and nullify argument after freeing.
Fix issues reported by static code analysis tool 'parfait'

Closes: #41235
Reported-by: Jiri Kukacka
testenv: add test to stress wget 1.16 crash
openssl backend: repair use of TLSv1+ protocols

The use of TLSv1_client_method() means that the protocol used will be
limited to TLSv1.0.  This is not desirable for --secure-protocol values
of "auto" (default) and "pfs".  Fix by using SSLv23_client_method() and
disabling SSLv[23].

Issue reported by Mikolaj Kucharski.