Only use <stdio_ext.h> if present

configure.ac

@@ -173,6 +173,7 @@ AC_CHECK_HEADERS([\
   dirent.h \
   pwd.h \
   grp.h \
+  stdio_ext.h \
 ])
 
 # Checks for typedefs, structures, and compiler characteristics.

src/fpurge.c

@@ -26,7 +26,9 @@
 
 #include <errno.h>
 #include <stdio.h>
+#if HAVE_STDIO_EXT_H
 #include <stdio_ext.h>
+#endif
 
 #ifdef HAVE___FPURGE
 int