ld-version: Fix awk regex compile failure

BugLink: http://bugs.launchpad.net/bugs/1558330

commit 4b7b1ef2 upstream.

The ld-version.sh script fails on some versions of awk with the
following error, resulting in build failures for MIPS:

awk: scripts/ld-version.sh: line 4: regular expression compile failed (missing '(')

This is due to the regular expression ".*)", meant to strip off the
beginning of the ld version string up to the close bracket, however
brackets have a meaning in regular expressions, so lets escape it so
that awk doesn't expect a corresponding open bracket.

Fixes: ccbef167 ("Kbuild, lto: add ld-version and ld-ifversion ...")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Tested-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Cc: Michal Marek <mmarek@suse.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kbuild@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12838/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

scripts/ld-version.sh

 #!/usr/bin/awk -f
 # extract linker version number from stdin and turn into single number
 	{
-	gsub(".*)", "");
+	gsub(".*\\)", "");
 	split($1,a, ".");
 	print a[1]*10000000 + a[2]*100000 + a[3]*10000 + a[4]*100 + a[5];
 	exit