Rollup merge of rust-lang#114172 - fortanix:raoul/fix_process-spawning_test, r=workingjubilee

Fix issue_15149 test for the SGX target

PR rust-lang#112390 moved tests to std. Unfortunately, this caused the `issue_15149` test to be enabled for the SGX target. This is incorrect as the SGX target does not support the `env::current_exe()` call.

Author: matthiaskrgr

library/std/tests/process_spawning.rs

@@ -1,3 +1,5 @@
+#![cfg(not(target_env="sgx"))]
+
 use std::env;
 use std::fs;
 use std::process;