plperl.h should #undef fstat along with stat and lstat.

Needed now that commit bed9075 caused win32_port.h to provide
a #define for that too.  Per buildfarm.

Author: tglsfdc

src/pl/plperl/plperl.h

@@ -92,6 +92,7 @@
 #undef bind
 #undef connect
 #undef fopen
+#undef fstat
 #undef kill
 #undef listen
 #undef lstat