For AIX, with both these configure variants:
  $ configure --prefix=/prefix --enable-shared CC=gcc CXX=g++ OPT=
  $ configure --prefix=/prefix --enable-shared --without-computed-gotos CC=xlc_r CXX=xlC_r OPT=
the output changes like this:

   $ PKG_CONFIG_PATH=/prefix/lib/pkgconfig pkg-config --libs python-3.4
old: -L/prefix/lib -lpython3.4m
new: -L/prefix/lib -lpython3.4m -Wl,-bE:/prefix/lib/python3.4/config-3.4m/python.exp -lld

   $ /prefix/bin/python3.4-config --ldflags
old:  -L/prefix/lib -lintl -ldl -lm  -lpython3.4m -Wl,-bE:Modules/python.exp -lld
new: -Wl,-bI:/prefix/lib/python3.4/config-3.4m/python.exp



For Linux, with this configure variant:
  $ configure --prefix=/prefix --enable-shared CC=gcc CXX=g++
the output changes like this:

  $ PKG_CONFIG_PATH=/prefix/lib/pkgconfig pkg-config --libs python-3.4
old: -L/prefix/lib -lpython3.4m
new: -L/prefix/lib -lpython3.4m -Xlinker -export-dynamic

   $ /prefix/bin/python3.4-config --ldflags
old:   -L/prefix/lib -lpthread -ldl  -lutil -lm  -lpython3.4m -Xlinker -export-dynamic
new: # Yes, nothing. Not sure if python modules should have undefined python symbols, or link against libpython.so

Just found out that distutils.command.build_ext.get_libraries() does add libpython.so for Linux and similar (not Darwin and AIX).
Actually, distutils.command.build_ext.get_libraries() should add $LINKFORMODULE instead now, so LDSHARED does not need to carry.

More thoughts?  (will post results with --disable-shared as separate comment)