ss: Fix compiler errors of unused return-values

Many errors when compiling with gcc 4.7.3 about unused return-values
upon the calls to fgets and fscanf:

ss.c: In function ‘user_ent_hash_build’:
ss.c:305:12: error: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Werror=unused-result]
ss.c: In function ‘get_slabstat’:
ss.c:387:7: error: ignoring return value of ‘fgets’, declared with attribute warn_unused_result [-Werror=unused-result]
ss.c: In function ‘init_service_resolver’:
ss.c:511:8: error: ignoring return value of ‘fgets’, declared with attribute warn_unused_result [-Werror=unused-result]
ss.c: In function ‘run_ssfilter’:
ss.c:728:11: error: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Werror=unused-result]
ss.c: In function ‘is_ephemeral’:
ss.c:550:10: error: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Werror=unused-result]
ss.c: In function ‘netlink_show’:
ss.c:2836:7: error: ignoring return value of ‘fgets’, declared with attribute warn_unused_result [-Werror=unused-result]
ss.c: In function ‘packet_show’:
ss.c:2630:7: error: ignoring return value of ‘fgets’, declared with attribute warn_unused_result [-Werror=unused-result]
ss.c: In function ‘unix_show’:
ss.c:2364:7: error: ignoring return value of ‘fgets’, declared with attribute warn_unused_result [-Werror=unused-result]
cc1: all warnings being treated as errors
make[1]: *** [ss.o] Error 1
make[1]: Leaving directory `/home/christoph/workspace/linux/iproute2/misc'
make: *** [all] Error 2

For the calls to fscanf we can't really do anything about it, and just
do an empty if-statement to make the compiler happy.

Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
lnstat: Fix compiler errors of unused return-values

Many errors when compiling with gcc 4.7.3 about unused return-values
upon the calls to fgets:

lnstat_util.c: In function ‘lnstat_scan_fields’:
lnstat_util.c:145:7: error: ignoring return value of ‘fgets’, declared with attribute warn_unused_result [-Werror=unused-result]
lnstat_util.c: In function ‘lnstat_update’:
lnstat_util.c:97:10: error: ignoring return value of ‘fgets’, declared with attribute warn_unused_result [-Werror=unused-result]
lnstat_util.c:111:9: error: ignoring return value of ‘fgets’, declared with attribute warn_unused_result [-Werror=unused-result]
lnstat_util.c: In function ‘scan_lines’:
lnstat_util.c:52:8: error: ignoring return value of ‘fgets’, declared with attribute warn_unused_result [-Werror=unused-result]
cc1: all warnings being treated as errors
make[1]: *** [lnstat_util.o] Error 1
make[1]: Leaving directory `/home/christoph/workspace/linux/iproute2/misc'
make: *** [all] Error 2

Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>