Working builds for RHEL 8 and RHEL 9

[yakatz]

So far this is the minimum change required to build on RHEL 8 and RHEL 9.

Current issues:

• rpc/rpc.h is no longer included in the main devel headers. The files can be found in the libtirpc-devel package and can be copied to the correct location. It isn't clear to me how to fix this without building a separate package for the headers.

• Some headers/libraries for ndmp are missing and I am not sure where to find them:

  ~/amanda/rpm/BUILD/amanda-4.0.0alpha.git.6fc36428/ndmp-src/.libs/libndmlib.so: undefined reference to `xdr_bytes'
  ~/amanda/rpm/BUILD/amanda-4.0.0alpha.git.6fc36428/ndmp-src/.libs/libndmlib.so: undefined reference to `xdr_u_long'
  ~/amanda/rpm/BUILD/amanda-4.0.0alpha.git.6fc36428/ndmp-src/.libs/libndmlib.so: undefined reference to `xdr_free'
  ~/amanda/rpm/BUILD/amanda-4.0.0alpha.git.6fc36428/ndmp-src/.libs/libndmlib.so: undefined reference to `xdr_array'
  ~/amanda/rpm/BUILD/amanda-4.0.0alpha.git.6fc36428/ndmp-src/.libs/libndmlib.so: undefined reference to `xdrrec_skiprecord'
  ~/amanda/rpm/BUILD/amanda-4.0.0alpha.git.6fc36428/ndmp-src/.libs/libndmlib.so: undefined reference to `xdr_string'
  ~/amanda/rpm/BUILD/amanda-4.0.0alpha.git.6fc36428/ndmp-src/.libs/libndmlib.so: undefined reference to `xdrrec_endofrecord'
  ~/amanda/rpm/BUILD/amanda-4.0.0alpha.git.6fc36428/ndmp-src/.libs/libndmlib.so: undefined reference to `xdr_void'
  ~/amanda/rpm/BUILD/amanda-4.0.0alpha.git.6fc36428/ndmp-src/.libs/libndmlib.so: undefined reference to `xdrrec_create'
  ~/amanda/rpm/BUILD/amanda-4.0.0alpha.git.6fc36428/ndmp-src/.libs/libndmlib.so: undefined reference to `xdr_enum'
  ~/amanda/rpm/BUILD/amanda-4.0.0alpha.git.6fc36428/ndmp-src/.libs/libndmlib.so: undefined reference to `xdr_short'
  ~/amanda/rpm/BUILD/amanda-4.0.0alpha.git.6fc36428/ndmp-src/.libs/libndmlib.so: undefined reference to `xdr_opaque'
  ~/amanda/rpm/BUILD/amanda-4.0.0alpha.git.6fc36428/ndmp-src/.libs/libndmlib.so: undefined reference to `xdr_u_char'
  ~/amanda/rpm/BUILD/amanda-4.0.0alpha.git.6fc36428/ndmp-src/.libs/libndmlib.so: undefined reference to `xdr_u_short'
  collect2: error: ld returned 1 exit status
  

  It is possible to build with the option --without-ndmp to get around this, but I don't know if this feature is commonly used and if that would be a showstopper.

• On RHEL9, xinetd is no longer available. systemd triggers are preferred instead. I am working on that part now.

[sidsbrmnn]

@yakatz I think you'll require both rpcgen and libtirpc-devel to compile NDMP. And yes, you're right. xinetd startup needs to be migrated to systemd services.