Makefile: Remove superfluous include path
arpa/nameser_compat.h: Use proper endian defines
Provide new rtems_bsdnet_rtrequest()

Delete superfluous code.
Delete obsolete _bsd_nexus_devices
Generalize linker sets

Add ability to create linker sets for items with an arbitrary type.
nexus: Fix resouce allocation
nexus: Use a linker set for the devices
testsuite: Make similar to default-network-init.h
testsuite: Add DEFAULT_NETWORK_NO_INTERFACE_0
ppp: Import from RTEMS sources
ppp: Port to new stack