Allow compiling non-32bit under feature flag

Cargo.toml

@@ -168,6 +168,7 @@ rustls_tls = ["mysql/default-rustls"]
 
 # internal feature-like things
 jobs = ["flume"]
+allow_non_32bit = []
 
 [dev-dependencies]
 regex = "1"

src/lib.rs

@@ -55,5 +55,5 @@ pub mod url;
 #[cfg(feature = "worleynoise")]
 pub mod worleynoise;
 
-#[cfg(not(target_pointer_width = "32"))]
-compile_error!("rust-g must be compiled for a 32-bit target");
+#[cfg(all(not(target_pointer_width = "32"), not(feature = "allow_non_32bit")))]
+compile_error!("Compiling for non-32bit is not allowed without enabling the `allow_non_32bit` feature.");