compare between unsigned integer and integer in PubSubClient.cpp

[spellbinder103]

when i compile INO file with Arduino IDE i saw some non-critical warning message, after i investigate i found some curious in PubSubClient.cpp file.

at line 481, unsigned int rc = 0; at line 487, int expectedLength; and... at line 523, return (rc == expectedLength);

compiler warning message is: comparison of integer expressions of different signedness: 'unsigned int' and 'int'

expectedLength shall change from int to unsigned int?