tests/system.rs Now correctly identifies apple clang

Previous regex didn't have proper capture group names, and the
regex didn't properly handle for spaces between `Apple` and
`clang version`. Updated to also support compiler output
like `Apple LLVM clang version` which I believe it used to do.

tests/system.rs

@@ -434,8 +434,8 @@ fn run_sccache_command_tests(compiler: Compiler, tempdir: &Path) {
             Err(e) => panic!("Invalid UTF-8 sequence: {}", e),
         };
 
-        // Apple clang would match "Apple LLVM version"
-        let re = Regex::new(r"(?P<apply>Apple+*)?clang version (?P<major>\d+)").unwrap();
+        // Regex to match "Apple LLVM clang version" or "Apple clang version"
+        let re = Regex::new(r"(?P<apple>Apple).+clang version (?P<major>\d+)").unwrap();
         let (major, is_appleclang) = match re.captures(version_output) {
             Some(c) => (
                 c.name("major").unwrap().as_str().parse::<usize>().unwrap(),