update travis OSX image to the latest version

.travis.yml

@@ -20,7 +20,7 @@ matrix:
     - env: cmake=1 toolset=gcc
     - env: variant=test_debug crypto=openssl docs=1 tests=1 examples=1 tools=1 python=1 toolset=darwin ios=1
       os: osx
-      osx_image: xcode9.2
+      osx_image: xcode11.2
     - env: arch=arm toolset=gcc-arm
 
 notifications:
@@ -216,6 +216,10 @@ script:
   # the same, in order for builds to be reused between invocations
   - export B2_ARGS="crypto=$crypto debug-iterators=on picker-debugging=on asserts=on invariant-checks=full $toolset variant=$variant"
 
+  - 'if [[ $TRAVIS_OS_NAME == "osx" && "$crypto" == "openssl" ]]; then
+    export B2_ARGS="${B2_ARGS} openssl-lib=/usr/local/opt/openssl@1.1/lib openssl-include=/usr/local/opt/openssl@1.1/include" ;
+    fi'
+
   - 'if [ "$check_headers" == "1" ]; then
       ${B2} -j3 check-headers ${B2_ARGS};
     fi'

Jamfile

@@ -28,20 +28,21 @@ if $(BOOST_ROOT)
 else
 {
 	local boost-lib-search-path =
-		<search>/usr/local/lib
+		<search>/usr/local/opt/boost/lib
 		;
 
 	local boost-include-path =
-		<include>/usr/local/include
-		<include>/usr/sfw/include
+		<include>/usr/local/opt/boost/include
 	;
 
-	# the names are decorated in MacPorts
+	# the names are decorated in MacPorts.
 	lib boost_system : : <target-os>darwin <name>boost_system-mt $(boost-lib-search-path)
 		: : $(boost-include-path) ;
 
-	lib boost_system : : <name>boost_system $(boost-lib-search-path)
-		: : $(boost-include-path) ;
+	# we can't add /usr/local/lib to the search path on mac, as that will
+	# interfere with system libraries (specifically libjpeg)
+	lib boost_system : : <name>boost_system $(boost-lib-search-path) <search>/usr/local/lib
+		: : $(boost-include-path) <include>/usr/local/include ;
 }
 
 VERSION = 1.2.2 ;
@@ -211,6 +212,9 @@ rule warnings ( properties * )
 
 # enable these warnings again, once the other ones are dealt with
 		result += <cflags>-Wno-weak-vtables ;
+
+		result += <cflags>-Wno-return-std-move-in-c++11 ;
+		result += <cflags>-Wno-unknown-warning-option ;
 	}
 
 	if <toolset>gcc in $(properties)