If these are ifdef WIN32 in the .c file, should be so in .h as well.

src/include/utils/palloc.h

@@ -21,7 +21,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/palloc.h,v 1.28 2004/08/08 06:44:35 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/utils/palloc.h,v 1.29 2004/08/08 16:13:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -80,9 +80,10 @@ extern char *MemoryContextStrdup(MemoryContext context, const char *string);
 
 #define pstrdup(str)  MemoryContextStrdup(CurrentMemoryContext, (str))
 
-/* Used for Win32 */
-void *pgport_palloc(Size sz);
-char *pgport_pstrdup(const char *str);
-void pgport_pfree(void *pointer);
+#ifdef WIN32
+extern void *pgport_palloc(Size sz);
+extern char *pgport_pstrdup(const char *str);
+extern void pgport_pfree(void *pointer);
+#endif
 
 #endif   /* PALLOC_H */