nptl/tst-thread-exit-clobber failure on armv7l-*-linux-gnueabihf

[Florian Weimer]

* Szabolcs Nagy:

> the arm _dl_runtime_resolve code does not seem to preserve fp regs,
> i'm not sure why that works, but we should look out for gcc-9 changes
> that may start using fp regs in the arm dynamic linker.

i386 has a test case for that, using objdump --disassemble.  See
sysdeps/i386/tst-ld-sse-use.sh.  It may be possible to reuse some ideas
from it.

Thanks,
Florian