Eliminate the mysterious games that the Cygwin build plays with the linker
flag variables. DLLLIBS is gone, use SHLIB_LINK like everyone else.
Detect cygipc in configure, after the linker flags are set up, otherwise
configure might not work at all.
Make sure everything is covered by make clean.
Fix the build of the new conversion procedure modules.
Add new DLLIMPORT markers where required.
Finally, the compiler complains if we use an explicit
-I/usr/local/include, so don't do that. Curiously, -L/usr/local/lib is
still necessary.
'make install'; there are enough of 'em that this slowed down the make
noticeably. Ensure that 'all' is the default make target in all these
directories (defaulting to 'make install' is surprising and dangerous
IMHO). Fix a couple small typos.
with OPAQUE, as per recent pghackers discussion. I still want to do some
more work on the 'cstring' pseudo-type, but I'm going to commit the bulk
of the changes now before the tree starts shifting under me ...
