texinfo patches (strictness): binutils, gdb, gcc

compilation errored out during documentation builds of binutils-2.22, gcc-4.6.3 and gdb-7.3.1.
this is due to new strictness in texinfo.

fixes include:
- replace first @itemx with @item inside @table
- moved comments from inline latex to texinfo (got falsely interpreted by texinfo)
- fixed an option inside a gcc getopts

there are still more non-critical warnings during compilation.

tested on updated archlinux x86_64.