auto merge of #13489 : JustAPerson/rust/crate-file-name, r=alexcrichton

Before, the `--crate-file-name` flag only checked crate attributes for
possible crate types. Now, if any type is specified by one or more
`--crate-type` flags, only the filenames for those types will be
emitted, and any types specified by crate attributes will be ignored.

src/test/run-make/obey-crate-type-flag/Makefile

@@ -0,0 +1,13 @@
+-include ../tools.mk
+
+# check that rustc builds all crate_type attributes
+# delete rlib
+# delete whatever dylib is made for this system
+# check that rustc only builds --crate-type flags, ignoring attributes
+# fail if an rlib was built
+all:
+	$(RUSTC) test.rs
+	rm $(TMPDIR)/libtest*.rlib
+	rm $(TMPDIR)/libtest*
+	$(RUSTC) --crate-type dylib test.rs
+	rm $(TMPDIR)/libtest*.rlib && exit 1 || exit 0

src/test/run-make/obey-crate-type-flag/test.rs

@@ -0,0 +1,13 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![crate_type = "rlib"]
+#![crate_type = "dylib"]
+