By default, the ld command only looks for *.a archives
to resolve library references.

To recognize dynamic shared libaries (*.so), two flags
need to be added to the Modules/ld_so_aix script: -brtl
-bnortllib

Line 170 in the script should read:

CCOPT="$CCOPT -Wl,-bM:SRE -Wl,-T512 -Wl,-H512 -brtl
-bnortllib -lm -o $objfile"

-brtl ... says you want to include libtk8.4.so 
   when searching for the library -ltk8.4

-bnortllib ... says you do not want the semantics of
the AIX "run time linking" services ... just the search
for the library.

This resolves a problem when Python is built with tk
support.