gold: configury: fix obsolete macros

gold: configury: fix obsolete macros

Running `autoreconf -vf -Wall' in the gold directory shows errors about the use
of obsolete macros.  This patch fix the issues with macros used directly by
configure.ac. However, it doesn't fix all warnings.  There are autoconf warnings
about macros from files in config and one automake warning about a target being
shadowed.  It cuts a lot of the noise down and makes an upgrade to autoconf
2.71+ easier.

https://www.gnu.org/software/automake/manual/1.12.2/html_node/Obsolete-Macros.html#index-AM_005fCONFIG_005fHEADER
https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/Obsolete-Macros.html#index-AC_005fOUTPUT-2133

gold/ChangeLog:

* aclocal.m4: Regenerate.
	* configure: Regenerate.
	* configure.ac: Replace AM_CONFIG_HEADER by AC_CONFIG_HEADERS. Replace
        AC_OUTPUT(file list) by AC_CONFIG_FILES([file list])\nAC_OUTPUT.

Approved-by: Alan Modra <amodra@gmail.com>