I tried to build postgresql packages, and lost on building the -docs
binary package because some of the html files (generated by pg release
process and in the tarball I think) had different names from the
PLIST.

I have send-pr'd the PLIST changes:

  pkg/26186: postgresql-docs incorrect PLIST

But, I ran

make print-PLIST > PLIST.new

and all the files under

share/doc/html/postgresql/

are missing.  I see in Packages.txt

   If the package installs files via tar(1) or other methods that don't update
   file access times, be sure to add these files manually to your PLIST,
   as 'find -newer' won't catch them!

but it would seem that using ctime rather than mtime would catch
these.  Has this been tried and found problematic?

I just did:

--- bsd.pkg.mk.~1.1463.~	Thu May 27 07:55:42 2004
+++ bsd.pkg.mk	Wed Jul  7 11:27:13 2004
@@ -4647,7 +4647,7 @@
 	"a.out")	genlinks=1 ;;					\
 	*)		genlinks=0 ;;					\
 	esac;								\
-	${FIND} ${PREFIX}/. -xdev -newer ${EXTRACT_COOKIE} \! -type d -print\
+	${FIND} ${PREFIX}/. -xdev -cnewer ${EXTRACT_COOKIE} \! -type d -print\
 	 | ${SORT}							\
 	 | ${AWK} '							\
 		{ sub("${PREFIX}/\\./", ""); }				\

and that gave me a much better PLIST.
But, I don't know how portable -cnewer is.