Remove a couple of unused functions, and fix a typeo.
Use "function(void)" instead of "function()" to declare 0-arg functions.

"function(void)" is the correct syntax in a function declaration, although
in practice compilers accept the latter too. It's OK in a function
definition, but change those too for consistency.

Michael Paquier and me.
Add missing function declarations.

These are not actually used outside of pgtypes.c, but let's be consistent
and declare them in pgtypes.h anyway.

Michael Paquier
Use the same CFLAGS/LDFLAGS to build regression tests as used to build driver.
Replace NOT_USE_LIBPQ with USE_LIBPQ #define.

This avoids the cumbersome double-negatives, "#ifndef NOT_USE_LIBPQ",
making the code easier to read.
Use the PG_CONFIG setting from ./configure cmd line in regression tests.

If compiling without libpq (configure --without-libpq), then you still need
to have pg_config in path to build the regression tests, or specify
PG_CONFIG at the make command line.
Add test/Makefile to .gitignore.

It's generated from test/Makefile.in now.
Add more test cases for ODBC catalog functions.

Michael Paquier