drop some rust compiler validation

--- a/build/moz.configure/rust.configure
+++ b/build/moz.configure/rust.configure
@@ -91,9 +91,6 @@ def unwrap_rustup(prog, name):
     return unwrap
 
 
-rustc = unwrap_rustup(rustc, "rustc")
-cargo = unwrap_rustup(cargo, "cargo")
-
 
 set_config("CARGO", cargo)
 set_config("RUSTC", rustc)
@@ -411,35 +408,6 @@ def assert_rust_compile(host_or_target, rustc_target, rustc):
 
         os.write(in_fd, ensure_binary(source))
         os.close(in_fd)
-
-        cmd = [
-            rustc,
-            "--crate-type",
-            "staticlib",
-            target_arg,
-            "-o",
-            out_path,
-            in_path,
-        ]
-
-        def failed():
-            die(
-                dedent(
-                    """\
-            Cannot compile for {} with {}
-            The target may be unsupported, or you may not have
-            a rust std library for that target installed. Try:
-
-              rustup target add {}
-            """.format(
-                        host_or_target.alias, rustc, rustc_target
-                    )
-                )
-            )
-
-        check_cmd_output(*cmd, onerror=failed)
-        if not os.path.exists(out_path) or os.path.getsize(out_path) == 0:
-            failed()
     finally:
         os.remove(in_path)
         os.remove(out_path)
@@ -462,29 +430,6 @@ def rust_host_triple(
     rustc_target = detect_rustc_target(
         host, compiler_info, arm_target, rust_supported_targets
     )
-    if rustc_target != rustc_host:
-        if host.alias == rustc_target:
-            configure_host = host.alias
-        else:
-            configure_host = "{}/{}".format(host.alias, rustc_target)
-        die(
-            dedent(
-                """\
-        The rust compiler host ({rustc}) is not suitable for the configure host ({configure}).
-
-        You can solve this by:
-        * Set your configure host to match the rust compiler host by editing your
-        mozconfig and adding "ac_add_options --host={rustc}".
-        * Or, install the rust toolchain for {configure}, if supported, by running
-        "rustup default stable-{rustc_target}"
-        """.format(
-                    rustc=rustc_host,
-                    configure=configure_host,
-                    rustc_target=rustc_target,
-                )
-            )
-        )
-    assert_rust_compile(host, rustc_target, rustc)
     return rustc_target