After Kris pointed out to me that I'm completely on the wrong track

wrt. the names of the installed doxygen temp files, do it right now,
and delete anything from the target directory doxygen did install
there which doesn't match our expectation (as take from PLIST_DOC).
This appears to be the only sane way until doxygen reverts itself back
to normal behaviour, and doesn't install any temporary files.

devel/avr-libc/Makefile

@@ -7,7 +7,7 @@
 
 PORTNAME=	avr-libc
 PORTVERSION=	1.2.3
-PORTREVISION=	3
+PORTREVISION=	4
 PORTEPOCH=	1
 CATEGORIES=	devel
 MASTER_SITES=	${MASTER_SITE_SAVANNAH}
@@ -52,6 +52,12 @@ DEMOFILES=	Makefile demo.c
 DEMOFILES+=	demo.bin demo.hex demo.pdf demo.srec
 .endif
 
+.if defined(MAINTAINER_DEBUG)
+ECHO_EXTRA_RM=	${ECHO_CMD} "Removing " $${to_be_rm_ed} "..."
+.else
+ECHO_EXTRA_RM=	${ECHO_CMD} "Removing extraneous man page files..."
+.endif
+
 do-build:
 		(cd ${BUILD_WRKSRC}; ${SETENV} ${MAKE_ENV} ./domake MAKE=${GMAKE})
 
@@ -83,8 +89,20 @@ do-install:
 				${PREFIX}/share/doc/avr-libc/examples/twitest; \
 		done
 .if !defined(NOPORTDOCS)
-		${RM} -f ${PREFIX}/share/doc/avr-libc/man/man3/_tmp*
-		${RM} -f ${PREFIX}/share/doc/avr-libc/man/man3/_work*
+		@( \
+		tmpname=$${TMPDIR:-/tmp}/avr-libc-inst.$$$$ ; \
+		cd ${PREFIX}/share/doc/avr-libc/man/man3 ; \
+		${GREP} '^share/doc/.*man3/' ${PLIST_DOC} | \
+			${SED} -e 's,.*/,,' | \
+			${SORT} > $${tmpname}.1 ; \
+		${LS} -1  | \
+			${SED} -e 's,.*/,,' | \
+			${SORT} > $${tmpname}.2 ; \
+		to_be_rm_ed=$$(${COMM} -13 $${tmpname}.1 $${tmpname}.2) ; \
+		${RM} -f $${tmpname}.1 $${tmpname}.2 ; \
+		${ECHO_EXTRA_RM} ; \
+		${RM} -f $${to_be_rm_ed} \
+		)
 .endif
 
 .include <bsd.port.mk>