Fix for issue: Compilers have to be configured in the pom.xml

The onlySpecifiedCompilers flag was being used incorrectly.

This meant you had to specify a compiler in the configuration section in order to compiler native code:

        <configuration>
          <c>
            <includes>
              <include>**/*.c</include>
            </includes>
          </c>
       </configuration>

This was a regression bug, earlier versions did not require this specification.  This include file information is already specified in aol.properties.