Introduce TargetPlatformIdentifier property for value comparisons

Author: Arlodotexe

MultiTarget/MultiTargetIdentifiers.props

@@ -43,7 +43,8 @@
 
     <IsUwp Condition="'$(IsUwp)' == '' AND $(UwpTargetFramework.Contains('$(TargetFramework);')) AND '$(UwpTargetFramework)' != '' AND '$(MultiTargetsUwp)' == 'true'">true</IsUwp>
     <IsWinAppSdk Condition="'$(IsWinAppSdk)' == '' AND $(WinAppSdkTargetFramework.Contains('$(TargetFramework);')) AND '$(WinAppSdkTargetFramework)' != '' AND '$(MultiTargetsWasdk)' == 'true'">true</IsWinAppSdk>
-    <IsWindowsTfm Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'windows'">true</IsWindowsTfm>
+    <TargetPlatformIdentifier>$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)'))</TargetPlatformIdentifier>
+    <IsWindowsTfm Condition="$(TargetPlatformIdentifier) == 'windows'">true</IsWindowsTfm>
 
     <IsDroid Condition="'$(IsDroid)' == '' AND $(AndroidLibTargetFramework.Contains('$(TargetFramework);')) AND '$(AndroidLibTargetFramework)' != '' AND '$(MultiTargetsDroid)' == 'true'">true</IsDroid>
     <IsMacOS Condition="'$(IsMacOS)' == '' AND $(MacOSLibTargetFramework.Contains('$(TargetFramework);')) AND '$(MacOSLibTargetFramework)' != '' AND '$(MultiTargetsMacOS)' == 'true'">true</IsMacOS>