removed lib .def file generation fix for UJSON4C

UJSON4C exported one function inappropriately, likely a remnant of how
the library was assembled.
The export was removed in the library, so the partial workaround
(anonymizing the symbol) is no longer needed.

driver/build_def.bat

@@ -16,6 +16,3 @@ echo.>> %OUTFILE%
 echo EXPORTS>> %OUTFILE%
 echo.>> %OUTFILE%
 powershell -NoLogo -ExecutionPolicy Bypass -Command %FILTER%>> %OUTFILE%
-echo.>> %OUTFILE%
-REM minimize the exposure of this unwanted export
-echo JSON_DecodeObject @1 NONAME PRIVATE>> %OUTFILE%