[test] Update tests to include location string.

test/libsolidity/syntaxTests/duplicateFunctions/fallback_function_twice.sol

@@ -4,4 +4,4 @@ contract C {
     fallback() external { x = 3; }
 }
 // ----
-// DeclarationError 7301: (64-94): Only one fallback function is allowed.
+// DeclarationError 7301: (64-94='fallback() external { x = 3; }'): Only one fallback function is allowed.

test/libsolidity/syntaxTests/duplicateFunctions/illegal_names_exception.sol

@@ -8,5 +8,5 @@ contract C {
 	}
 }
 // ----
-// Warning 2319: (61-88): This declaration shadows a builtin symbol.
-// Warning 2319: (90-118): This declaration shadows a builtin symbol.
+// Warning 2319: (61-88='function this() public { 	}'): This declaration shadows a builtin symbol.
+// Warning 2319: (90-118='function super() public { 	}'): This declaration shadows a builtin symbol.

test/libsolidity/syntaxTests/duplicateFunctions/illegal_names_functions.sol

@@ -12,6 +12,6 @@ contract C {
 // ----
 // DeclarationError 3726: (17-78): The name "_" is reserved.
 // DeclarationError 3726: (84-117): The name "super" is reserved.
-// DeclarationError 3726: (123-155): The name "this" is reserved.
+// DeclarationError 3726: (123-155='function this() internal {     }'): The name "this" is reserved.
 // Warning 2319: (84-117): This declaration shadows a builtin symbol.
-// Warning 2319: (123-155): This declaration shadows a builtin symbol.
+// Warning 2319: (123-155='function this() internal {     }'): This declaration shadows a builtin symbol.

test/libsolidity/syntaxTests/duplicateFunctions/receive_function_thrice.sol

@@ -4,5 +4,5 @@ contract C {
     receive() external payable { }
 }
 // ----
-// DeclarationError 4046: (52-82): Only one receive function is allowed.
-// DeclarationError 4046: (87-117): Only one receive function is allowed.
+// DeclarationError 4046: (52-82='receive() external payable { }'): Only one receive function is allowed.
+// DeclarationError 4046: (87-117='receive() external payable { }'): Only one receive function is allowed.