COMP: Missig .cxx for library build of the PThreadPool.

Change-Id: I878f847aa29fd5d8b0296dfa017fe3fabf875a0e
COMP: Add header guards and copyright statements.

There were missing header guards and copyright statements that were causing
compilation failures for examples and tests.

Change-Id: If1ca85d364478d53409c7c583d1ba827ef7d623a
COMP: Add return for non-void function.

Change-Id: Iac2bcf132655adb7bcfaa9c0d7e2cbf9fc20cb16