Add explicit support for being installed into a system triggered with --enable-fhs-paths.

Add two mechanism for avoiding name-collisions in a system-wide
installation of charybdis. The ssld and bandb daemons, intended to be
directly used by ircd and not the user, install into libexec when
--enable-fhs-paths is set. For binaries which are meant to be in PATH
(bindir), such as ircd and viconf, there is now an option
--with-program-prefix=progprefix inspired by automake. If the user
specifies --with-program-prefix=charybdis, the ircd binary is named
charybdisircd when installed.

Add support for saving the pidfile to a rundir and storing the ban
database in localstatedir instead of in sysconfdir. This is, again,
conditional on --enable-fhs-paths.

Fix(?) genssl.sh to always write created SSL key/certificate/dh
parameters to the sysconfdir specified during ./configure. The
previous behavior was to assume that the user ran genssl.sh after
ensuring that his current working directory was either sysconfdir or a
sibling directory of sysconfdir.

extensions/Makefile.in

@@ -16,7 +16,14 @@ INSTALL_PROGRAM	= @INSTALL_PROGRAM@
 INSTALL_DATA	= @INSTALL_DATA@
 INSTALL_SUID    = @INSTALL_PROGRAM@ -o root -m 4755
 SHELL		= /bin/sh
-AUTOMODULEDIR	= @moduledir@/extensions
+
+prefix          = @prefix@
+exec_prefix     = @exec_prefix@
+libdir          = @libdir@
+pkglibdir       = @pkglibdir@
+moduledir       = @moduledir@
+PACKAGE_TARNAME = @PACKAGE_TARNAME@
+AUTOMODULEDIR	= $(moduledir)/extensions
 
 SSL_LIBS	= @SSL_LIBS@
 SSL_INCLUDES	= @SSL_INCLUDES@