last release we lost our reassuring msg when no local python install

was found.  Restore warm fuzzy msg.  Text is now

  Looking for installed Python version XXX

followed by either

  Got it!
or
  'import site' failed; use -v for traceback
  No installed Python found.
  Only built-in modules are available.  Some scripts may not run.
  Continuing happily.


And while we are at it, clean up a couple of compiler warnings.

source/blender/python/BPY_extern.h

@@ -30,6 +30,9 @@
  * ***** END GPL/BL DUAL LICENSE BLOCK *****
  */
 
+#ifndef BPY_EXTERN_H
+#define BPY_EXTERN_H
+
 extern char bprogname[];	/* holds a copy of argv[0], from creator.c */
 
 struct Text; /* defined in DNA_text_types.h */
@@ -93,3 +96,5 @@ extern "C" {
 #ifdef __cplusplus
 }				/* extern "C" */
 #endif
+
+#endif  /* BPY_EXTERN_H */