Boost: Update last known MSVC version to VS2017.3

Change-Id: I41952279cc9d40769bfc51dd0f03c0b0624815d2
Reviewed-on: https://gerrit.libreoffice.org/41961Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Grzegorz Araminowicz <g.araminowicz@gmail.com>
Reviewed-by: Michael Stahl <mstahl@redhat.com>

external/boost/UnpackedTarball_boost.mk

@@ -39,6 +39,10 @@ boost_patches += clang-cl.patch.0
 boost_patches += boost_1_60_0.undef.warning.patch
 boost_patches += boost_1_63_0.undef.warning.patch.1
 
+# Silence unknown-compiler-warning for MSVC version 19.11.25506:
+# https://github.com/boostorg/config/pull/177/commits/a0147b73e8bde8f4b2c19c96166353dba8fa9914
+boost_patches += boost_1_63_0.msvs2017.3.warning.patch.1
+
 $(eval $(call gb_UnpackedTarball_UnpackedTarball,boost))
 
 $(eval $(call gb_UnpackedTarball_set_tarball,boost,$(BOOST_TARBALL)))

external/boost/boost_1_63_0.msvs2017.3.warning.patch.1

+diff -ru boost.orig/boost/config/compiler/visualc.hpp boost/boost/config/compiler/visualc.hpp
+--- boost.orig/boost/config/compiler/visualc.hpp	2016-12-22 13:33:14.000000000 +0100
++++ boost/boost/config/compiler/visualc.hpp	2017-09-05 21:33:16.462142600 +0200
+@@ -293,8 +293,8 @@
+ #endif
+ 
+ //
+-// last known and checked version is 19.10.24629 (VC++ 2017 RC):
+-#if (_MSC_VER > 1910)
++// last known and checked version is 19.11.25506 (VC++ 2017.3):
++#if (_MSC_VER > 1911)
+ #  if defined(BOOST_ASSERT_CONFIG)
+ #     error "Unknown compiler version - please run the configure tests and report the results"
+ #  else