hardlink: fix compiler warnings [-Wsign-compare -Wmaybe-uninitialized]]

hardlink: fix compiler warnings [-Wsign-compare -Wmaybe-uninitialized]]

misc-utils/hardlink.c: In function ‘process_path’:
misc-utils/hardlink.c:287:30: warning: operand of ?: changes signedness from ‘off_t’ {aka ‘long int’} to ‘long unsigned int’ due to unsignedness of other operand [-Wsign-compare]

misc-utils/hardlink.c: In function ‘main’:
misc-utils/hardlink.c:455:5: warning: ‘exclude_pattern’ may be used uninitialized in this function [-Wmaybe-uninitialized]

Signed-off-by: Karel Zak <kzak@redhat.com>