Add missing docs for feature added by Richard Henderson.

* doc/cpp.texi (__SSP__, __SSP_ALL__): Document.
* doc/invoke.texi (-Wstack-protector, -fstack-protector,
-fstack-protector-all, --param ssp-buffer-size): Document.
(-Wvariadic-macros): Alphabetize.
(-fsched-stalled-insns-dep): Add missing 'f'.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@103057 138bc75d-0d04-0410-961f-82ee72b054a4