Temporarily mark lib.msun.{cbrt_test.cbrtl_powl,trig_test.reduction} expected failure after clang700-import merge

[lwhsu]

Summary

Temporarily mark lib.msun.{cbrt_test.cbrtl_powl,trig_test.reduction}
expected failure after clang700-import merge

PR: 234040

[ngie]

This skips testing on all architectures and compilers.

It would make more sense (and I should have done this before), to do something along the lines of:

#if defined(__amd64__) && defined(__clang__) && __clang_major__ > 7
    atf_tc_expect_fail("test fails with clang 7+ - bug 234040");
#endif

[lwhsu]

Mark expected failure only on amd64 with clang7+

[ngie]

[markj]

Approved