configure gaps

While trying to build PostgreSQL 9.0 on a machine where the SA had 
omitted to install a lot of the required packages, I noticed a couple of 
cases where configure passed but the build failed due to missing pieces 
in the toolset.

Specifically, a) when python was installed but python-devel was not, 
configure passed by the compile for python failed quite miserably, and 
b) with gettext installed but not gettext-tools (and in particular 
xgettext was missing), the NLS stuff failed.

I'm, not sure if this is worth fixing, but it seemed worth mentioning. 
ISTM that if we pass configure, we should be able to assume that the 
requisite build tools, libraries, include files etc. are present.

cheers

andrew