Revert portable feature as it doesn't do anything (#871)

* Revert "Update README.md with a new section for the portable feature"

This reverts commit 0d8804a.

* Revert "Add portable feature for RocksDB build"

This reverts commit eeab5d8.

---------

Co-authored-by: zaidoon <zaidoon@cloudflare.com>

Cargo.toml

@@ -34,7 +34,6 @@ bzip2 = ["librocksdb-sys/bzip2"]
 rtti = ["librocksdb-sys/rtti"]
 multi-threaded-cf = []
 serde1 = ["serde"]
-portable = ["librocksdb-sys/portable"]
 
 [dependencies]
 libc = "0.2"

README.md

@@ -54,21 +54,9 @@ the crate feature `multi-threaded-cf`, which makes this binding's
 data structures use `RwLock` by default. Alternatively, you can directly create
 `DBWithThreadMode<MultiThreaded>` without enabling the crate feature.
 
-## Portable builds
-
-RocksDB's build, unlike Cargo, will default to setting `-march=native`, which
-generate code that fully takes advantage of build machine's CPU's features.
-This may create a binary that isn't compatible with other CPUs on the same
-architecture. For example, building on a machine with AVX512 support will create
-a binary that fails with `SIGILL` on machines without AVX512.
-
-Set the `portable` feature on this crate to pass `PORTABLE=1` to RocksDB's build,
-which will create a portable binary at the cost of some performance.
-
 ## Switch between /MT or /MD run time library (Only for Windows)
 
 The feature `mt_static` will request the library to be built with [/MT](https://learn.microsoft.com/en-us/cpp/build/reference/md-mt-ld-use-run-time-library?view=msvc-170)
 flag, which results in library using the static version of the run-time library.
 *This can be useful in case there's a conflict in the dependecy tree between different
 run-time versions.*
-

librocksdb-sys/Cargo.toml

@@ -24,7 +24,6 @@ zstd = ["zstd-sys"]
 zlib = ["libz-sys"]
 bzip2 = ["bzip2-sys"]
 rtti = []
-portable = []
 
 [dependencies]
 libc = "0.2"

librocksdb-sys/build.rs

@@ -90,10 +90,6 @@ fn build_rocksdb() {
         config.define("USE_RTTI", Some("1"));
     }
 
-    if cfg!(feature = "portable") {
-        config.define("PORTABLE", Some("1"));
-    }
-
     config.include(".");
     config.define("NDEBUG", Some("1"));