dnsdist: add missing lmdb dep

Currently dnsdist is failing at packaging stage when lmdb is in staging:

make[4]: Leaving directory '/builder/shared-workdir/build/sdk/build_dir/target-x86_64_musl/dnsdist-1.4.0'
Package dnsdist is missing dependencies for the following libraries:
liblmdb.so
Makefile:109: recipe for target '/builder/shared-workdir/build/sdk/bin/packages/x86_64/packages/dnsdist_1.4.0-2_x86_64.ipk' failed

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>

net/dnsdist/Makefile

@@ -66,7 +66,7 @@ define Package/dnsdist
   CATEGORY:=Network
   SUBMENU:=IP Addresses and Names
   TITLE:=dnsdist DNS-, DOS- and abuse-aware loadbalancer
-  DEPENDS:=+DNSDIST_OPENSSL:libopenssl +DNSDIST_GNUTLS:libgnutls +protobuf +re2 +libcap +libedit +libfstrm +lua +boost +libnetsnmp +libatomic +libsodium +DNSDIST_DNS_OVER_HTTPS:libh2o-evloop
+  DEPENDS:=+DNSDIST_OPENSSL:libopenssl +DNSDIST_GNUTLS:libgnutls +protobuf +re2 +libcap +libedit +libfstrm +lmdb +lua +boost +libnetsnmp +libatomic +libsodium +DNSDIST_DNS_OVER_HTTPS:libh2o-evloop
   URL:=https://dnsdist.org/
 endef