cython: Fix for LibTool compilation and Python 3 libintl

On Python 3.9 `libpython` no longer is linkable as a static library
due to the fact that `libpython` now depends on `libintl`.  This would
mean we would have to import `libintl` to create a fully linked .la

It is better to be explicit that we are building a .so (really a .dylib
but autotools uses linux file conventions) that doesn't have to be fully
diff --git a/cython/ b/cython/
index 20618d7..4079977 100644
--- a/cython/
+++ b/cython/
@@ -39,7 +39,7 @@
 	-Wno-implicit-function-declaration \
-plist_la_LDFLAGS = -module -avoid-version $(PYTHON_LIBS) $(AM_LDFLAGS) -no-undefined
+plist_la_LDFLAGS = -module -avoid-version $(PYTHON_LIBS) $(AM_LDFLAGS) -shared -export-dynamic
 plist_la_LIBADD = $(top_builddir)/src/
 plist.c: plist.pyx $(PXDINCLUDES) $(PXIINCLUDES)