patch 7.4.907
Problem:    Libraries for dynamically loading interfaces can only be defined
            at compile time.
Solution:   Add options to specify the dll names. (Kazuki Sakamoto,
            closes #452)
diff --git a/src/if_python3.c b/src/if_python3.c
index a6a655f..721e3cc 100644
--- a/src/if_python3.c
+++ b/src/if_python3.c
@@ -686,7 +686,12 @@
     int
 python3_enabled(int verbose)
 {
-    return py3_runtime_link_init(DYNAMIC_PYTHON3_DLL, verbose) == OK;
+#ifdef WIN3264
+    char *dll = DYNAMIC_PYTHON3_DLL;
+#else
+    char *dll = *p_py3dll ? (char *)p_py3dll : DYNAMIC_PYTHON3_DLL;
+#endif
+    return py3_runtime_link_init(dll, verbose) == OK;
 }
 
 /* Load the standard Python exceptions - don't import the symbols from the