When llvm-config can't be found, report this
When llvm-config can't be executed, mention this in the error.
@@ -11,7 +11,7 @@ fn main() {
let cxxflags = Command::new("llvm-config")
.args(&["--cxxflags"])
.output()
- .unwrap();
+ .expect("could not execute llvm-config");
let cxxflags = String::from_utf8(cxxflags.stdout).unwrap();
