librocksdb_sys: use tikv-jemalloc-sys (#520) (#522)

Jemallocator has not been active for several months. We published our
own fork, which upgraded jemalloc to 5.2.1.
Signed-off-by: Jay Lee <BusyJayLee@gmail.com>

librocksdb_sys/Cargo.toml

@@ -19,7 +19,7 @@ tempfile = "3.1"
 [features]
 default = []
 encryption = ["openssl-sys"]
-jemalloc = ["jemalloc-sys"]
+jemalloc = ["tikv-jemalloc-sys"]
 # portable doesn't require static link, though it's meaningless
 # when not using with static-link right now in this crate.
 portable = ["libtitan_sys/portable"]
@@ -30,8 +30,8 @@ cc = "1.0.3"
 cmake = "0.1"
 bindgen = "0.51"
 
-[dependencies.jemalloc-sys]
-version = "0.1.7"
+[dependencies.tikv-jemalloc-sys]
+version = "0.4.0"
 optional = true
 features = ["unprefixed_malloc_on_supported_platforms"]