package/python-numpy: fix fenv build failure on ARC with glibc

package/python-numpy: fix fenv build failure on ARC with glibc

Building python-numpy on ARC with glibc fails due to missing FE_*
definitions in <fenv.h>. These exceptions are not supported by
ARC architecture. Let's add patch, which disables compilation
of a part of the code in which FE_* errors occur for ARC.

ARCompact toolchain issues are already fixed in the latest toolchain.
Also since commit "311af5e8c2db887800639bc803c8201b6b70e9ce"
("toolchain/toolchain-buildroot: enable glibc for all little-endian
ARCs with atomic ops") glibc is available for ARCompact.
That is why in Config.in we are leaving only "BR_arc" and
removing comments, which are not actual.

Signed-off-by: Evgeniy Didin <didin@synopsys.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: arc-buildroot@synopsys.com
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>