[compiler-rt] [safestack] Silent overflow.c test on aarch64

The safestack overflow.c test is currently failing on an aarch64
buildbot with a segfault, but it is currently passing on other
configuration.

This patch silent the issue for now on aarch64 by setting to all
supported architectures the 'stable-runtime' configure and set
the test to requires it.

llvm-svn: 255491

compiler-rt/test/safestack/lit.cfg

@@ -22,3 +22,8 @@ if config.lto_supported:
 # SafeStack tests are currently supported on Linux, FreeBSD and Darwin only.
 if config.host_os not in ['Linux', 'FreeBSD', 'Darwin']:
    config.unsupported = True
+
+# Allow tests to use REQUIRES=stable-runtime.  For use when you cannot use XFAIL
+# because the test fail due some runtime issue.
+if config.target_arch != 'aarch64':
+  config.available_features.add('stable-runtime')

compiler-rt/test/safestack/overflow.c

@@ -7,6 +7,8 @@
 // Test that buffer overflows on the unsafe stack do not affect variables on the
 // safe stack.
 
+// REQUIRES: stable-runtime
+
 __attribute__((noinline))
 void fct(volatile int *buffer)
 {