Add no-fail-fast support to miri, rustfmt and clippy testsuites

This commit adds `--no-fail-fast` flag to each `cargo test`
command in each tool Step trait implementation.

Fixes rust-lang#108261

Author: Jesus Checa Hidalgo

src/bootstrap/test.rs

@@ -435,6 +435,10 @@ impl Step for Rustfmt {
             &[],
         );
 
+        if !builder.fail_fast {
+            cargo.arg("--no-fail-fast");
+        }
+
         let dir = testdir(builder, compiler.host);
         t!(fs::create_dir_all(&dir));
         cargo.env("RUSTFMT_TEST_DIR", dir);
@@ -615,6 +619,10 @@ impl Step for Miri {
         );
         cargo.add_rustc_lib_path(builder, compiler);
 
+        if !builder.fail_fast {
+            cargo.arg("--no-fail-fast");
+        }
+
         // miri tests need to know about the stage sysroot
         cargo.env("MIRI_SYSROOT", &miri_sysroot);
         cargo.env("MIRI_HOST_SYSROOT", sysroot);
@@ -746,6 +754,10 @@ impl Step for Clippy {
             &[],
         );
 
+        if !builder.fail_fast {
+            cargo.arg("--no-fail-fast");
+        }
+
         cargo.env("RUSTC_TEST_SUITE", builder.rustc(compiler));
         cargo.env("RUSTC_LIB_PATH", builder.rustc_libdir(compiler));
         let host_libs = builder.stage_out(compiler, Mode::ToolRustc).join(builder.cargo_dir());