src/filemanager/chmod.c: fix -Wsign-conversion warnings:
chmod.c:245:41: warning: implicit conversion changes signedness: 'unsigned int' to 'int' [-Wsign-conversion]
chmod.c:266:41: warning: implicit conversion changes signedness: 'unsigned int' to 'int' [-Wsign-conversion]
chmod.c:321:49: warning: implicit conversion changes signedness: 'unsigned int' to 'int' [-Wsign-conversion]
chmod.c:352:72: warning: implicit conversion changes signedness: 'int' to 'button_flags_t' [-Wsign-conversion]
chmod.c:357:72: warning: implicit conversion changes signedness: 'int' to 'button_flags_t' [-Wsign-conversion]
chmod.c:367:42: warning: implicit conversion changes signedness: 'int' to 'button_flags_t' [-Wsign-conversion]
chmod.c:371:42: warning: implicit conversion changes signedness: 'int' to 'button_flags_t' [-Wsign-conversion]
Signed-off-by: Andreas Mohr <and@gmx.li>
Signed-off-by: Andrew Borodin <aborodin@vmail.ru>