When I attempted to install the following gem on FC6, the gem supplied krb5.h file was out of date and the gem couldn't
compile.  It seems that the current krb5.h file referrences the com_err.h file in et/com_err.h as opposed to com_err.h
as in the supplied file.  By removing the krb5.h file from the project and also from the extconf.rb file, make resolves
the dependency using the standard include path and the build works.  I tested with the example.rb file and it works
fine.  I think this is a safer way to deploy the gem without having to worry about the krb5.h file changing.

A patch is attached that removes the dependency.