Mention BSD/OS find_typedef behavior.

src/tools/find_typedef

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-# $PostgreSQL: pgsql/src/tools/find_typedef,v 1.14 2009/06/11 03:14:08 momjian Exp $
+# $PostgreSQL: pgsql/src/tools/find_typedef,v 1.15 2009/06/12 03:04:48 momjian Exp $
 
 # This script attempts to find all typedef's in the postgres binaries
 # by using 'nm' to report all typedef debugging symbols.
@@ -53,6 +53,8 @@ do	# if objdump -W is recognized, only one line of error should appear
 		egrep -A3 '\(DW_TAG_typedef\)' |
 		awk ' $1 == "DW_AT_name" {print $NF}'
 	else	# BSD/OS
+		# BSD/OS reports all typedefs, even those defined in system
+		# include files but never referenced in the PG code.
 		objdump --stabs "$DIR"/* |
 		awk ' $2 == "LSYM" && $7 ~ /:t/ {sub(":.*", "", $7); print $7}'
 	fi