adding bcel library option to ant formula

Hello,

Could you please add additional option --with-bcel to ant formula?
ant requires this library when examining classes for properties, for example:
```
<loadproperties srcfile="${build}/com/VersionContainer.class" encoding="ISO-8859-1">
	<filterchain>
		<classconstants />
		<prefixlines prefix="java.credits." />
	</filterchain>
</loadproperties>
<echo message="Version found ${java.credits.VERSION}" />
```
(VersionContainer.class contains VERSION field)

If bcel jar is not available in libexec/lib, ant will throw NoClassDefFoundError:
```
BUILD FAILED
java.lang.NoClassDefFoundError: org/apache/bcel/classfile/ClassParser
        at org.apache.tools.ant.filters.util.JavaClassHelper.getConstants(JavaClassHelper.java:47)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
```

Thank you