Don't require po4a at build time.
http://bugs.gentoo.org/269905

--- realpath-1.14-orig/po/Makefile	2009-02-22 12:56:47.000000000 +0100
+++ realpath-1.14/po/Makefile	2009-05-19 23:45:26.000000000 +0200
@@ -4,5 +4,5 @@
 #
 
 ALL_TARGET=
-SUBDIRS=bin man
+SUBDIRS=bin
 include ../common.mk