BUG #4951: installation dir wrong for libpq compilation

The following bug has been logged online:

Bug reference:      4951
Logged by:          Jim Michaels
Email address:      jmichae3@yahoo.com
PostgreSQL version: 8.4.0
Operating system:   Win XP Pro Sp3
Description:        installation dir wrong for libpq compilation
Details:

it is impossible to compile in libpq headers unless the installation
directory for postgres has no spaces.  compilers such as gcc/mingw don't
like that.

you had it right the first time for 8.3.7 installing pgsql in
c:\postgresplus.  even if it's c:\postgresql that would be fine, just as
long as it's not
c:\program files\postgresql.

besides, on vista c:\program files is a protected directory, and writes to
that directory may end up somewhere else in a virtual store if the program
does not have a vista-compatible manifest.

I get loads of errors saying things are not defined, and an error at the top
saying it could not find libpq.h.