fix windows tests

Windows has a different error message than POSIX, so the ui tests fail for the clippy-config-fail tests.
This commit splits those tests up in target-os specific subdirectories and extends compile-test.rs to
run either of them based on the target os. Here's hope we'll get a green appveyor build.

tests/compile-test.rs

@@ -29,4 +29,6 @@ fn compile_test() {
     prepare_env();
     run_mode("run-pass", "run-pass");
     run_mode("ui", "ui");
+    #[cfg(target_os = "windows")] run_mode("ui-windows", "ui");
+    #[cfg(not(target_os = "windows"))] run_mode("ui-posix", "ui");
 }

tests/ui-windows/conf_bad_toml.rs

@@ -0,0 +1,6 @@
+// error-pattern: error reading Clippy's configuration file
+
+#![feature(plugin)]
+#![plugin(clippy(conf_file="./tests/compile-fail/conf_bad_toml.toml"))]
+
+fn main() {}

tests/ui-windows/conf_bad_toml.stderr

@@ -0,0 +1,4 @@
+error: error reading Clippy's configuration file: The system cannot find the file specified. (os error 2)
+
+error: aborting due to previous error
+

tests/ui-windows/conf_bad_toml.toml

@@ -0,0 +1,2 @@
+fn this_is_obviously(not: a, toml: file) {
+}

tests/ui-windows/conf_bad_type.rs

@@ -0,0 +1,6 @@
+// error-pattern: error reading Clippy's configuration file: `blacklisted-names` is expected to be a `Vec < String >` but is a `integer`
+
+#![feature(plugin)]
+#![plugin(clippy(conf_file="./tests/compile-fail/conf_bad_type.toml"))]
+
+fn main() {}

tests/ui-windows/conf_bad_type.stderr

@@ -0,0 +1,4 @@
+error: error reading Clippy's configuration file: The system cannot find the file specified. (os error 2)
+
+error: aborting due to previous error
+

tests/ui-windows/conf_bad_type.toml

@@ -0,0 +1 @@
+blacklisted-names = 42

tests/ui-windows/conf_non_existant.rs

@@ -0,0 +1,6 @@
+// error-pattern: error reading Clippy's configuration file
+
+#![feature(plugin)]
+#![plugin(clippy(conf_file="./tests/auxiliary/non_existant_conf.toml"))]
+
+fn main() {}

tests/ui-windows/conf_non_existant.stderr

@@ -0,0 +1,4 @@
+error: error reading Clippy's configuration file: The system cannot find the file specified. (os error 2)
+
+error: aborting due to previous error
+