rack: Fix ECN on finalizing session.

[rscheff]

Summary

Maintain code similarity between RACK and base stack
for ECN. This may not strictly be necessary, depending
when a state transition to FIN_WAIT_1 is done in RACK
after a shutdown() or close() syscall.

See D29616

MFC after: 3 days

sys/netinet/tcp_stacks/rack.c

 PLIST_SUB+=        ARCH="${KMK_ARCH}"
 
 KMK_BUILDDIR=        ${WRKSRC}/out/${KMK_ARCH}/${KMK_BUILDTYPE}
 KMK_CONFIG=        VBOX_LIBPATH_X11=${LOCALBASE} VBOX_FREEBSD_SRC=${SRC_BASE}/sys
 KMK_FLAGS+=     -j${MAKE_JOBS_NUMBER}
 
 .include <bsd.port.pre.mk>
 
-.if ${OPSYS} == FreeBSD
-.if ${OSVERSION} >= 1400059
-BROKEN=                Fails to compile with libc++ 14.0.3
-.elif ${OSVERSION} >= 1301000 && ${OSVERSION} < 1400000
-BROKEN=                Fails to compile: error: ran out of registers during register allocation
-.endif
-.endif
-
-.if ${CHOSEN_COMPILER_TYPE} == clang && ${OPSYS} == FreeBSD && ${OSVERSION} > 1400022
-# clang > 11 included in FreeBSD 14 fails to compile this legacy version
-# of virtualbox-ose, force clang 11 on FreeBSD 14 where a newer clang is
-# included.
+.if ${CHOSEN_COMPILER_TYPE} == clang && ${OPSYS} == FreeBSD && \
+    (${OSVERSION} < 1302505 || (${OSVERSION} >= 1400000 && ${OSVERSION} < 1400079))
+# llvm 13 and 14 included in FreeBSD fails to compile this legacy version of
+# virtualbox-ose, force llvm 15 on all versions of the FreeBSD except lastest 13
+# and 14 where the llvm 15 is included: PR#265539.
+# Keep possibility to define different llvm via VBOX_LLVM_VER in make.conf.
 BUILD_DEPENDS+=        clang${VBOX_LLVM_VER}:devel/llvm${VBOX_LLVM_VER}
 CC=             clang${VBOX_LLVM_VER}
 CXX=            clang++${VBOX_LLVM_VER}
-VBOX_LLVM_VER?= 11
+VBOX_LLVM_VER?= 15
 .endif
 
 .if ${PYTHON_MAJOR_VER} >= 3
 PLIST_SUB+=     PYTHON_PYCDIR=/__pycache__/ \
                 PYTHON_PYCEXT=.cpython-${PYTHON_SUFFIX}.pyc
 .else
 PLIST_SUB+=     PYTHON_PYCDIR=/ \
                 PYTHON_PYCEXT=.pyc