package/grpc: fix build on non-NPTL systems

package/grpc: fix build on non-NPTL systems

uClibc-ng in non-NPTL configurations doesn't implement
pthread_setname_np(). Unfortunately grpc assumes that as soon as
__GLIBC__ is defined, pthread_setname_np() is available. It is
particularly sad, because grpc build system uses CMake, so it is
trivial to do such a check.

This commit adds a patch that does just this: check for the
availability of pthread_setname_np(), and use it only if
available. The patch has been submitted upstream.

Fixes:

  http://autobuild.buildroot.org/results/47991306abbcd80fb8e6baad0bd7490fa74f696c/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>