GCN back-end config

GCN back-end config

This patch contains the configuration adjustments needed to enable the GCN
back-end.

The new configure check for dlopen is required to allow building the new
gcn-run tool.  This tool uses libdl to load the HSA runtime libraries, which
are required to run programs on the GPU.  The tool is disabled if libdl is not
available.

2019-01-17  Andrew Stubbs  <ams@codesourcery.com>
	    Kwok Cheung Yeung  <kcy@codesourcery.com>
	    Julian Brown  <julian@codesourcery.com>
	    Tom de Vries  <tom@codesourcery.com>
	    Jan Hubicka  <hubicka@ucw.cz>
	    Martin Jambor  <mjambor@suse.cz>

	* configure.ac: Likewise.
	* configure: Regenerate.
	* contrib/config-list.mk: Add amdgcn-amdhsa.

	gcc/
	* config.gcc: Add amdgcn*-*-amdhsa configuration.
	* configure.ac: Check for dlopen.
	* configure: Regenerate.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@268024 138bc75d-0d04-0410-961f-82ee72b054a4