Why are these modules built without respecting my LDFLAGS?

I have a short list of modules that have been built without respecting my 
LDFLAGS and/or LDFLAGS_SL. They are as follows:
 autoinc.so citext.so earthdistance.so insert_username.so isn.so lo.so moddatetime.so refint.so tablefunc.so
timetravel.sotsearch2.so
 

I have looked around in the documentation and the source code, but have found 
nothing enlightening.

Is there a way to force them to be built with my LDFLAGS? Is it a bad idea? If 
so, why?

Sincerely, Aaron W. Swenson