Update crate name used for build script probe

This will make it correctly respect RUSTC_BOOTSTRAP=thiserror.

Author: dtolnay

build.rs

@@ -39,7 +39,7 @@ fn compile_probe() -> bool {
 
     cmd.stderr(Stdio::null())
         .arg("--edition=2018")
-        .arg("--crate-name=thiserror_build")
+        .arg("--crate-name=thiserror")
         .arg("--crate-type=lib")
         .arg("--emit=metadata")
         .arg("--out-dir")