leveldb: update .hgignore to look more like $GOROOT/.hgignore.
leveldb: update .hgignore to look more like $GOROOT/.hgignore.

R=bradfitz, r
CC=golang-dev
http://codereview.appspot.com/6053043

bryanxu/leveldb-go,yh453926638/leveldb,gaowenbin/leveldb,patterncat/leveldb-go,shadowpriest/leveldb-go,iTalant/leveldb-go,mikewiacek/leveldb,bonbizin/leveldb-go,henderjon/leveldb-go,peterjliu/leveldb-go,scalingdata/leveldb-go,jhawk28/leveldb-go,bryanxu/leveldb-go,eryx/leveldb-go,oulan/leveldb-go,golang/leveldb,shadowpriest/leveldb-go,shaunstanislaus/leveldb,oulan/leveldb-go,gaowenbin/leveldb,cxflag203/leveldb-go,eryx/leveldb-go,golang/leveldb,henderjon/leveldb-go,patterncat/leveldb-go,mikewiacek/leveldb,jhawk28/leveldb-go,yh453926638/leveldb,bonbizin/leveldb-go,cxflag203/leveldb-go,scalingdata/leveldb-go,shaunstanislaus/leveldb,peterjliu/leveldb-go,iTalant/leveldb-go