Prevent empty lines in stack-trace of error messages on Windows

and avoid explicit use of StringBuilder.

Author: HannesWell

org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/markers/MavenMarkerManager.java

@@ -163,13 +163,11 @@ private String getRootErrorMessage(Throwable ex) {
   }
 
   private String getErrorMessage(Throwable ex) {
-    StringBuilder message = new StringBuilder();
-    if(ex.getMessage() != null) {
-      message.append(ex.getMessage()).append("\n\n");
-    }
-    StringWriter errorStackTrace = new StringWriter();
-    ex.printStackTrace(new PrintWriter(errorStackTrace));
-    return message.append(errorStackTrace).toString();
+    String exMessage = ex.getMessage();
+    StringWriter stackTrace = new StringWriter();
+    ex.printStackTrace(new PrintWriter(stackTrace));
+    String stackString = stackTrace.toString().replace("\r\n", "\n");
+    return exMessage != null ? exMessage + "\n\n" + stackString : stackString;
   }
 
   private Throwable getRootCause(Throwable ex) {