Include pthread.h in AudioResamplerSinc

Currently it gets included through utils/Log.h which includes
log/log.h which will usually be taken as:

system/core/liblog/include/log/log.h.

If on the other hand system/core/liblog/include_vndk/log/log.h gets
included instead, pthread.h will not be included.

Test: Manual - builds OK
Bug: 119390863
Change-Id: I64255f0812367a55996a7b64da65646fdf1743c2