where EXEC_BACKEND is defined

I noticed that when you want to define EXEC_BACKEND, perhaps to do some 
non-Windows testing of that option, it's not clear how to do that.  I 
would have expected it in pg_config_manual.h, but it's actually in 
configure.in and in MSBuildProject.pm.  So if you want to define it 
yourself, you kind of have to make up your own way to do it.

I don't see why this should be like that.  I propose the attached patch 
to move the thing to pg_config_manual.h.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services