Add llvm_components_contain to run-make-support

Author: Rejyr

src/tools/run-make-support/src/lib.rs

@@ -429,6 +429,13 @@ pub fn assert_not_contains(haystack: &str, needle: &str) {
     }
 }
 
+/// Check that `component` is in the `LLVM_COMPONENTS` variable.
+pub fn llvm_components_contain(component: &str) -> bool {
+    let llvm_components = env_var("LLVM_COMPONENTS");
+    // llvm_components is a list of space-separated words
+    format!(" {llvm_components} ").contains(&format!(" {component} "))
+}
+
 /// This function is designed for running commands in a temporary directory
 /// that is cleared after the function ends.
 ///