package/python-numpy: disable numpy if fenv.h is not provided by libc

With a C library which does not provide fenv.h, it won't work at runtime:
Crash after an "import numpy" on python.

Since numpy v1.16.0:
"Alpine Linux (and other musl c library distros) support
We now default to use fenv.h for floating point status error reporting.
Previously we had a broken default that sometimes would not report
underflow, overflow, and invalid floating point operations. Now we can
support non-glibc distrubutions like Alpine Linux as long as they ship
fenv.h."

Disable python-numpy for uClibc to avoid the runtime errors.

ARC's glibc used to have an incomplete fenv.h, but this has been fixed
since commit be0aaaae ("toolchain: bump ARC tools to arc-2019.03
release"), so we don't need an exception for ARC.

Two patches attempted to fix the build for uclibc and glibc for ARC, but
didn't fix the runtime issue. Remove those patches.

Signed-off-by: Damien DUVAL <damien.duval@smile.fr>
Signed-off-by: Alexandre PAYEN <alexandre.payen@smile.fr>
Cc: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
Signed-off-by: Romain Naour <romain.naour@smile.fr>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>