On a target that defaults to -mlong-double-64 -msse,
standard_abi_usable.cc and other tests fail to compile because of the
assert that rejects long double. As on ppc, we can trivially make
things work for -mlong-double-64.
for libstdc++-v3/ChangeLog
* include/experimental/bits/simd.h (__intrinsic_type): Accept
64-bit long doubles on x86 SSE.
35bd360eed