Log Message:
www/siege: Fix installation if ${PKG_SYSCONFBASE} != ${PREFIX}/etc.

The software Makefiles try to install example configuration files
directly into $(sysconfdir), which is set during the configure
stage to ${PKG_SYSCONFDIR} == ${PREFIX}/etc/siege.  However, pkgsrc
standards require that the example configuration files be installed
into ${PREFIX}/share/examples/siege ( ${EGDIR} ).

Pass sysconfdir=${EGDIR} to the bmake(1) process during the install
stage so that the Makefile recipe will install the example files
into the correct location.

Remove the "install" substitution class that was trying to do the
same thing but which fails if ${PKG_SYSCONFBASE} != ${PREFIX}/etc.

Bump the PKGREVISION due to changes in the installed files if the
package is built with default settings.  Fix discussed with nils@
in private correspondence.