buildroot

motion: fix build on musl

Some toolchains (musl) have pthread_setname_np but not pthread_getname_np.
The first patch fixes check on pthread_setname_np and the second one add
a check for pthread_getname_np

Fixes:

  http://autobuild.buildroot.net/results/65534775c5977e2424c5f5c63c46f9d0f39d7e1b

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>