Clean up various left over commented lines from dlopen to single
libhamlib transition. Remove unneeded configure variables.
Correct minor inconsistencies in Makefile.am files.
Define a new variable, READLINE_LIBS, so that only programs that offer
Readline support are linked against it.
Fix various compilation warnings and errors in test files revealed with
'make check' on MinGW.
Define rig and rotor backends to (mostly) be built in alphabetical
order.
Moved all backend *.h files into the SOURCES primary as Automake
documentation states all source file types should be listed. This
causes Automake to include *.h files in rebuild rules for the targets.
Removed the '-DIN_HAMLIB' assignment from the CFLAGS primary in each
backend and assigned it to AM_CPPFLAGS in configure.ac. The effect is
the same and it simplifies the backend Makefile.am files.
Removed all commented lines.
The Automake manual makes it clear that certain user variables such as
CC, CFLAGS, CXXFLAGS, CPPFLAGS, and so on are to be preserved for the
user running configure. This patch cleans up such assignments and
assures that PTHREAD_CFLAGS and so forth are applied to those targets
that require it.