testlib: Sync up QTest::LogElementType with element names

539553a572 renamed the LET_Error element
enum to LET_Message, without renaming the corresponding "error" element
name. This was not an issue in practice, since we never write the actual
element in QTestJUnitStreamer, but the two should be in sync to avoid
any confusion.

Pick-to: 6.2
Change-Id: I6c29f5303393b5f36b2f9877940bf3f6eaf3b7d2
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/testlib/qtestcoreelement_p.h

@@ -139,6 +139,7 @@ const char *QTestCoreElement<ElementType>::elementName() const
         "testcase",
         "testsuite",
         "benchmark",
+        "message",
         "system-err",
         "system-out"
     };

src/testlib/qtestelementattribute_p.h

@@ -89,12 +89,13 @@ namespace QTest {
         LET_Property = 0,
         LET_Properties = 1,
         LET_Failure = 2,
-        LET_Message = 3,
+        LET_Error = 3,
         LET_TestCase = 4,
         LET_TestSuite = 5,
         LET_Benchmark = 6,
-        LET_SystemError = 7,
-        LET_SystemOutput = 8
+        LET_Message = 7,
+        LET_SystemError = 8,
+        LET_SystemOutput = 9
     };
 }