Use dynamic linking for many things; disable jemallocator as it seems
to conflict with libc jemalloc, causing weird test assertion failures

--- Cargo.toml.orig	2019-12-15 00:01:33 UTC
+++ Cargo.toml
@@ -110,7 +110,7 @@ derive_is_enum_variant = "0.1.1"
 leveldb = { git = "https://github.com/timberio/leveldb", optional = true, default-features = false }
 db-key = "0.0.5"
 headers = "0.2.1"
-rdkafka = { git = "https://github.com/timberio/rust-rdkafka", features = ["ssl"], optional = true }
+rdkafka = { version = "0.22", features = ["ssl", "dynamic_linking", "external_lz4"], optional = true }
 hostname = "0.1.5"
 seahash = "3.0.6"
 jemallocator = { version = "0.3.0", optional = true }
@@ -114,7 +114,7 @@
 seahash = "3.0.6"
 jemallocator = { version = "0.3.0", optional = true }
 lazy_static = "1.3.0"
-rlua = { git = "https://github.com/timberio/rlua" }
+rlua = { git = "https://github.com/timberio/rlua", default-features = false, features = ["system-lua"] }
 num_cpus = "1.10.0"
 bytesize = "1.0.0"
 grok = "~1.0.1"
@@ -163,14 +163,14 @@ trust-dns-proto = "0.8.0"
 
 [features]
 # Default features for *-unknown-linux-gnu and *-apple-darwin
-default = ["vendored", "unix", "leveldb-plain", "rdkafka-plain"]
+default = ["unix", "leveldb-plain", "rdkafka-plain"]
 # Default features for *-unknown-linux-musl
 default-musl = ["vendored", "unix", "leveldb-cmake", "rdkafka-cmake"]
 # Default features for *-pc-windows-msvc
 default-msvc = ["vendored", "leveldb-cmake", "rdkafka-cmake"]
 
 # Enables features that work only on systems providing `cfg(unix)
-unix = ["jemallocator", "shiplift/unix-socket"]
+unix = ["shiplift/unix-socket"]
 # Forces vendoring of OpenSSL and ZLib dependencies
 vendored = ["openssl/vendored", "libz-sys/static"]
 # This feature is less portable, but doesn't require `cmake` as build dependency