devel/mdb: Update to 20210810 snapshot.

This update pulls in dim@'s earlier fix for building with clang 12
as well as an additional fix for breakage caused by a recent OpenZFS
change to remove avl_size.

Sponsored by:	Netflix

devel/mdb/Makefile

@@ -1,6 +1,5 @@
 PORTNAME=	mdb
-PORTVERSION=	20210125
-PORTREVISION=	1
+PORTVERSION=	20210810
 CATEGORIES=	devel
 
 MAINTAINER=	jhb@FreeBSD.org
@@ -13,7 +12,7 @@ USES=		compiler uidfix
 USE_GITHUB=	yes
 GH_ACCOUNT=	bsdjhb
 GH_PROJECT=	illumos-gate
-GH_TAGNAME=	60ff9f11c2
+GH_TAGNAME=	df212e0857
 
 ONLY_FOR_ARCHS=	amd64
 

devel/mdb/distinfo

@@ -1,3 +1,3 @@
-TIMESTAMP = 1611606942
-SHA256 (bsdjhb-illumos-gate-20210125-60ff9f11c2_GH0.tar.gz) = ac9419140ff4068b664d51ce648fec0ee007ea6fad9ccfa3a3d29de1fcd96d98
-SIZE (bsdjhb-illumos-gate-20210125-60ff9f11c2_GH0.tar.gz) = 115110163
+TIMESTAMP = 1628630438
+SHA256 (bsdjhb-illumos-gate-20210810-df212e0857_GH0.tar.gz) = 3daaeefbb7d44215672069868244ed46003c67db96d40858a3d85aa85d5ecffd
+SIZE (bsdjhb-illumos-gate-20210810-df212e0857_GH0.tar.gz) = 115100615

devel/mdb/files/patch-mdb_Makefile

@@ -1,11 +0,0 @@
---- mdb/Makefile.orig	2021-01-25 20:32:57 UTC
-+++ mdb/Makefile
-@@ -201,7 +201,7 @@ CWARNFLAGS.clang+= \
- 	-Wno-shadow \
- 	-Wno-sign-compare \
- 	-Wno-strict-prototypes \
--	-Wno-error-tautological-pointer-compare \
-+	-Wno-error=tautological-pointer-compare \
- 	-Wno-unused-parameter
- 
- .if ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 100000 || \