Update tests to match the messages

Author: nagisa

src/test/compile-fail/dupe-symbols-1.rs

@@ -17,5 +17,5 @@ pub fn a() {
 
 #[export_name="fail"]
 pub fn b() {
-//~^ symbol `fail` already exists
+//~^ symbol `fail` is already defined
 }

src/test/compile-fail/dupe-symbols-2.rs

@@ -20,6 +20,6 @@ mod a {
 mod b {
     #[no_mangle]
     pub extern fn fail() {
-    //~^ symbol `fail` already exists
+    //~^ symbol `fail` is already defined
     }
 }

src/test/compile-fail/dupe-symbols-3.rs

@@ -17,5 +17,5 @@ pub fn a() {
 
 #[no_mangle]
 pub fn fail() {
-//~^ symbol `fail` already exists
+//~^ symbol `fail` is already defined
 }

src/test/compile-fail/dupe-symbols-4.rs

@@ -27,5 +27,5 @@ impl A for B {
 impl A for C {
     #[no_mangle]
     fn fail(self) {}
-    //~^ symbol `fail` already exists
+    //~^ symbol `fail` is already defined
 }

src/test/compile-fail/dupe-symbols-5.rs

@@ -16,5 +16,5 @@ static HELLO: u8 = 0;
 
 #[export_name="fail"]
 pub fn b() {
-//~^ symbol `fail` already exists
+//~^ symbol `fail` is already defined
 }

src/test/compile-fail/dupe-symbols-6.rs

@@ -15,4 +15,4 @@ static HELLO: u8 = 0;
 
 #[export_name="fail"]
 static HELLO_TWICE: u16 = 0;
-//~^ symbol `fail` already exists
+//~^ symbol `fail` is already defined

src/test/compile-fail/dupe-symbols-7.rs

@@ -8,14 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 //
-#![crate_type="rlib"]
+// error-pattern: entry symbol `main` defined multiple times
 #![allow(warnings)]
 
-extern {
-    fn fail();
-}
-
-#[export_name="fail"]
-pub fn a() {
-//~^ symbol `fail` already exists
-}
+#[no_mangle]
+fn main(){}