Patch to avoid IP_DONTFRAG bug in latest xcode with broken Big Sur SDK

cmake/StaticBuild.cmake

@@ -232,6 +232,7 @@ add_static_target(expat expat_external libexpat.a)
 
 build_external(unbound
   DEPENDS openssl_external expat_external
+  PATCH_COMMAND patch -p1 -i ${PROJECT_SOURCE_DIR}/contrib/patches/unbound-no-apple-dontfrag.patch
   CONFIGURE_COMMAND ./configure ${cross_host} ${cross_rc} --prefix=${DEPS_DESTDIR} --disable-shared
   --enable-static --with-libunbound-only --with-pic
   --$<IF:$<BOOL:${WITH_LTO}>,enable,disable>-flto --with-ssl=${DEPS_DESTDIR}

contrib/patches/unbound-no-apple-dontfrag.patch

@@ -0,0 +1,11 @@
+--- a/services/listen_dnsport.c	2020-11-16 20:07:44.494582149 -0400
++++ b/services/listen_dnsport.c	2020-11-16 20:07:31.074585943 -0400
+@@ -533,7 +533,7 @@
+ 				return -1;
+ 			}
+ 		}
+-#  elif defined(IP_DONTFRAG)
++#  elif defined(IP_DONTFRAG) && !defined(__APPLE__)
+ 		int off = 0;
+ 		if (setsockopt(s, IPPROTO_IP, IP_DONTFRAG, 
+ 			&off, (socklen_t)sizeof(off)) < 0) {