src: silence compiler warnings

src: silence compiler warnings

cache.c:504:22: warning: ‘chain’ may be used uninitialized in this function [-Wmaybe-uninitialized]
cache.c:504:22: warning: ‘table’ may be used uninitialized in this function [-Wmaybe-uninitialized]
erec.c:128:16: warning: ‘line’ may be used uninitialized in this function [-Wmaybe-uninitialized]
optimize.c:524:9: warning: ‘line’ may be used uninitialized in this function [-Wmaybe-uninitialized]

Fixes: 8ad4056e9182 ("erec: expose print_location() and line_location()")
Fixes: afbd102211dc ("src: do not use the nft_cache_filter object from mnl.c")
Fixes: fb298877ece2 ("src: add ruleset optimization infrastructure")
Signed-off-by: Florian Westphal <fw@strlen.de>