[libstdc++] [testsuite] no libatomic for vxworks

libatomic hasn't been ported to vxworks.  Most of the stdatomic.h and
<atomic> underlying requirements are provided by builtins and libgcc,
and the vxworks libc already provides remaining __atomic symbols, so
porting libatomic doesn't seem to make sense.

However, some of the target arch-only tests in
add_options_for_libatomic cover vxworks targets, so we end up
attempting to link libatomic in, even though it's not there.
Preempt those too-broad tests.

Co-Authored-By: Marc Poulhiès <poulhies@adacore.com>
for  libstdc++-v3/ChangeLog

	* testsuite/lib/dg-options.exp (add_options_for_libatomic):
	None for *-*-vxworks*.

diff --git a/libstdc++-v3/testsuite/lib/dg-options.exp b/libstdc++-v3/testsuite/lib/dg-options.exp
index 84f9e3ebc730c8cd7d602db36449189b9686eee2..0d77fb029b09b1777dd9732fd774c3bbd2da99fb 100644 (file)
--- a/libstdc++-v3/testsuite/lib/dg-options.exp
+++ b/libstdc++-v3/testsuite/lib/dg-options.exp
@@ -338,6 +338,11 @@ proc atomic_link_flags { paths } {
 }
 
 proc add_options_for_libatomic { flags } {
+    # We don't (need to) build libatomic for vxworks.  Don't try to
+    # link it in, even on arches that support libatomic.
+    if { [istarget *-*-vxworks*] } {
+       return $flags
+    }
     if { [istarget hppa*-*-hpux*]
         || ([istarget powerpc*-*-*] && [check_effective_target_ilp32])
         || [istarget riscv*-*-*]