Add the following patch to the files directory:

--- Configure	2007-12-28 16:59:27.000000000 +0100
+++ Configure	2007-12-28 16:59:42.000000000 +0100
@@ -86,7 +86,7 @@
 		CC ?= gcc
 		CFLAGS += -g -O \$(DFLAGS) -Wall
 		LIBS = -lm -lc
-		DFLAGS= -DHASSELECT -DNEEDGTIME -DFREEBSD
+		DFLAGS= -DPOSIX -DHASSELECT -DNEEDGTIME -DFREEBSD
 EoF
 	;;
     sco*)