[7.3.x] Fix build with texinfo-5.0

Same as https://android-review.googlesource.com/#/c/69726 for gcc and
https://android-review.googlesource.com/#/c/69740

 for binutils.

This is backport from trunk:

2012-06-15  Patrice Dumas  <pertusus@free.fr>  (tiny change)

    * gdb.texinfo (Summary): Add a link to "Free Documentation".
    (Free Documentation): Add @node line.
    (Continuing and Stepping) <advance location>: Use @item instead of
    @itemx.
    (Reverse Execution) <set exec-direction reverse>: Use @item instead of
    @itemx.
    (Embedded Processors): Put the link to "PA" to its correct place,
    according to document structure.
    (Python API): Put the link to "Lazy Strings In Python" to its
    correct place.
    (Index): Use @@ in @tex block to get a literal @.

    * gdbint.texinfo: Fix the @subtitle line.

    * stabs.texinfo (Top): Put the link to "Symbol Types Index" to its
    correct place.

2013-01-07  Patrice Dumas  <pertusus@free.fr>

    * ld.texinfo: Replace @ with @@ when it is part of the text.
    Correct ordering of M68HC11 entry.

    * doc/binutils.texi: Fix ordering of top level nodes.
    Replace erroneous uses of @itemx with @item.

    * bfd.texinfo: Replace @ with @@ when it is part of the text.

Change-Id: I6c686092c8cd5c6dac401b3803e8519b1d2d96f2
Signed-off-by: Pavel Chupin <pavel.v.chupin@intel.com>