Fix latex quotes in <pre>

Commit 2073b3b removed \char but left its backslash. \char is not
necessary if fontenc is used. If fontenc is not used the curly
braces prevent interpretation as an umlaut.

src/latexgen.cpp

@@ -2364,7 +2364,7 @@ void filterLatexString(TextStream &t,const QCString &str,
                    break;
         case '\\': t << "\\textbackslash{}";
                    break;
-        case '"':  t << "\\\"{}";
+        case '"':  t << "\"{}";
                    break;
         case '`':  t << "\\`{}";
                    break;