Update GCC to autoconf 2.69, automake 1.15.1

[Simon Marchi]

On 2018-10-30 11:26 p.m., Joseph Myers wrote:
> This patch (diffs to generated files omitted below) updates GCC to use
> autoconf 2.69 and automake 1.15.1.  (That's not the latest automake
> version, but it's the one used by binutils-gdb, with which consistency
> is desirable, and in any case seems a useful incremental update that
> should make a future update to 1.16.1 easier.)

Whenever you feel like bumping gcc to 1.16.1, I can take care of binutils-gdb.

Simon