patch 8.0.1654: warnings for conversion of void to function pointer

Problem:    Warnings for conversion of void to function pointer.
Solution:   Use a temp variable that is a function pointer.
diff --git a/src/if_python.c b/src/if_python.c
index 8ba1241..02e2cd7 100644
--- a/src/if_python.c
+++ b/src/if_python.c
@@ -672,7 +672,8 @@
 python_runtime_link_init(char *libname, int verbose)
 {
     int i;
-    void *ucs_as_encoded_string;
+    PYTHON_PROC *ucs_as_encoded_string =
+				   (PYTHON_PROC*)&py_PyUnicode_AsEncodedString;
 
 #if !(defined(PY_NO_RTLD_GLOBAL) && defined(PY3_NO_RTLD_GLOBAL)) && defined(UNIX) && defined(FEAT_PYTHON3)
     /* Can't have Python and Python3 loaded at the same time.
@@ -711,14 +712,12 @@
 
     /* Load unicode functions separately as only the ucs2 or the ucs4 functions
      * will be present in the library. */
-    ucs_as_encoded_string = symbol_from_dll(hinstPython,
+    *ucs_as_encoded_string = symbol_from_dll(hinstPython,
 					     "PyUnicodeUCS2_AsEncodedString");
-    if (ucs_as_encoded_string == NULL)
-	ucs_as_encoded_string = symbol_from_dll(hinstPython,
+    if (*ucs_as_encoded_string == NULL)
+	*ucs_as_encoded_string = symbol_from_dll(hinstPython,
 					     "PyUnicodeUCS4_AsEncodedString");
-    if (ucs_as_encoded_string != NULL)
-	py_PyUnicode_AsEncodedString = ucs_as_encoded_string;
-    else
+    if (*ucs_as_encoded_string == NULL)
     {
 	close_dll(hinstPython);
 	hinstPython = 0;