src/libpcp/src/exec.c: add missing __pmInitLocks() calls
src/libpcp/src/exec.c: add missing __pmInitLocks() calls

On call paths directly from client to libpcp.

As a result the local mutext exec_lock was not being initialized.

Found on Mac OS X by qa/036 ... on other platforms I guess we've
just been lucky or the pthread mutex implementation is more
forgiving elsewhere.

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp