Removed warnings from nfsstat.c

Removed warnings from nfsstat.c

nfsstat.c: In function 'print_callstats':
nfsstat.c:797: warning: comparison between signed and unsigned integer
expressions
nfsstat.c:801: warning: comparison between signed and unsigned integer
expressions
nfsstat.c:802: warning: comparison between signed and unsigned integer
expressions
nfsstat.c:805: warning: comparison between signed and unsigned integer
expressions

nfsstat.c: In function 'print_callstats_list':
nfsstat.c:821: warning: comparison between signed and unsigned integer
expressions
nfsstat.c:828: warning: comparison between signed and unsigned integer
expressions

nfsstat.c: In function 'unpause':
nfsstat.c:1111: warning: unused parameter 'sig'
Signed-off-by: Steve Dickson <steved@redhat.com>