Restrict the pr86763 test to *-*-linux* targets

clock_gettime is not available on some baremetal targets
and may require -lrt on some non-linux targets.

gcc/testsuite/ChangeLog:

	* g++.dg/torture/pr86763.C: Restrict to *-*-linux*.

From-SVN: r263694

gcc/testsuite/ChangeLog

+2018-08-21  Szabolcs Nagy  <szabolcs.nagy@arm.com>
+
+	* g++.dg/torture/pr86763.C: Restrict to *-*-linux*.
+
 2018-08-21  Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
 	PR middle-end/86121

gcc/testsuite/g++.dg/torture/pr86763.C

-// { dg-do run }
+// { dg-do run { target { *-*-linux* } } }
 // { dg-additional-options "-fschedule-insns2 -fstrict-aliasing" }
-// { dg-additional-options "-lrt" { target *-*-linux-gnu } }
+// { dg-additional-options "-lrt" }
 
 #include <cstdint>
 #include <cassert>