Unlock access to File monitor singleton
Unlock access to File monitor singleton

Added corresponding unlock for file monitoring singleton lock. Related to gh-2057 fix (#2170).

Fixes gh-2371

Signed-off-by: Sridhar Meda <4c7fcba0a8a1e8d26ffef9db12f8e0218c968927@lexisnexis.com>

afishbeck/HPCC-Platform,afishbeck/HPCC-Platform,afishbeck/HPCC-Platform,afishbeck/HPCC-Platform,afishbeck/HPCC-Platform,afishbeck/HPCC-Platform