Avoid libgcc -NaN narrowing bug

Avoid libgcc -NaN narrowing bug

Forwarded: yes
Applied-Upstream: https://github.com/abseil/abseil-cpp/commit/1bae23e32ba1f1af7c7d1488a69a351ec96dc98d

When testing -NaN parsing, avoid narrowing -NaN from double to float. This
avoids a bug in libgcc (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98251).

The author works at Google. Upstream applied this patch as Piper revision
347654751 and exported it to GitHub; the Applied-Upstream URL above points to
the exported commit.

Gbp-Pq: Name nan-narrowing.diff