getline: protect prototype better

[Simon Josefsson]

How about this?  If for some reason HAVE_DECL_GETLINE is not defined
at all, the header file fail to parse.  This uses the idiom that is
suggested by the autoconf manual.

2005-08-23  Simon Josefsson  <address@hidden>

        * getline.h (getline): Protect prototype better.

--- getline.h   17 Jul 2005 11:39:14 +0200      1.16
+++ getline.h   23 Aug 2005 13:28:13 +0200      
@@ -23,6 +23,6 @@
 # include <stdio.h>
 # include <sys/types.h>
 
-#if !HAVE_DECL_GETLINE
+#if defined(HAVE_DECL_GETLINE) && !HAVE_DECL_GETLINE
 ssize_t getline (char **lineptr, size_t *n, FILE *stream);
 #endif /* !HAVE_GETLINE */