Fix VB defines

Preprocessor symbols in VB need to be combined with a comma, not a
semicolon.

src/Compilers/Test/Utilities/VisualBasic/BasicCompilerTestUtilities.vbproj

@@ -63,14 +63,14 @@
     <DefineDebug>true</DefineDebug>
     <DefineTrace>true</DefineTrace>
     <DebugType>full</DebugType>
-    <DefineConstants>$(DefineConstants);ARM</DefineConstants>
+    <DefineConstants>$(DefineConstants),ARM</DefineConstants>
     <PlatformTarget>ARM</PlatformTarget>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|ARM'">
     <Optimize>true</Optimize>
     <DefineTrace>true</DefineTrace>
     <DebugType>pdbonly</DebugType>
-    <DefineConstants>$(DefineConstants);ARM</DefineConstants>
+    <DefineConstants>$(DefineConstants),ARM</DefineConstants>
     <PlatformTarget>ARM</PlatformTarget>
   </PropertyGroup>
   <ItemGroup>

src/Samples/VisualBasic/ConsoleClassifier/ConsoleClassifierVB.vbproj

@@ -65,7 +65,7 @@
     <OutputPath>bin\Debug\</OutputPath>
     <DocumentationFile>ConsoleClassifier.xml</DocumentationFile>
     <NoWarn>42016,41999,42017,42018,42019,42032,42036,42020,42021,42022</NoWarn>
-    <DefineConstants>$(DefineConstants);_MyType="Empty"</DefineConstants>
+    <DefineConstants>$(DefineConstants),_MyType="Empty"</DefineConstants>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <PlatformTarget>AnyCPU</PlatformTarget>

src/Workspaces/VisualBasic/Desktop/BasicWorkspace.Desktop.vbproj

@@ -15,7 +15,7 @@
     <RestorePackages>true</RestorePackages>
   </PropertyGroup>
   <PropertyGroup Condition="'$(MSBuildAssemblyNameFragment)' == 'v12.0'">
-    <DefineConstants>$(DefineConstants);MSBUILD12</DefineConstants>
+    <DefineConstants>$(DefineConstants),MSBUILD12</DefineConstants>
   </PropertyGroup>
   <ItemGroup Label="File References">
     <Reference Include="Microsoft.Build, Version=$(VisualStudioReferenceAssemblyVersion), Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />