Update to Ubuntu 18 (#63)

Author: BrennanConroy

.azure/default-build.yml

@@ -26,7 +26,7 @@ jobs:
       ${{ if eq(parameters.agentOs, 'macOS') }}:
         vmImage: macOS-10.15
       ${{ if eq(parameters.agentOs, 'Linux') }}:
-        vmImage: ubuntu-16.04
+        vmImage: ubuntu-18.04
       ${{ if eq(parameters.agentOs, 'Windows') }}:
         vmImage: windows-2019
     steps:
@@ -74,4 +74,4 @@ jobs:
       inputs:
         testRunner: junit
         testResultsFiles: '$(Build.ArtifactStagingDirectory)/testOut/**/*.xml'
-        testRunTitle: ${{ parameters.agentOs }}-unit_test
+        testRunTitle: ${{ parameters.agentOs }}-unit_test

src/signalrclient/messagepack_hub_protocol.cpp

@@ -11,6 +11,7 @@
 #include <msgpack.hpp>
 #include "binary_message_parser.h"
 #include "binary_message_formatter.h"
+#include <cmath>
 
 namespace signalr
 {
@@ -429,4 +430,4 @@ namespace signalr
     }
 }
 
-#endif
+#endif