Update dndxc to modern versions (#2722)

dndxc was expecting generator formatting that wasn't used with visual
studio 2019. As a result, it built dndxc for x86, which couldn't load
the x64 dxcompiler.dll. It also didn't alow use of target versions past 6.3.

This changes the cmake logic to use a more reliable variable to
determine CPU type and adds stage versions up to 6.5.

tools/clang/tools/dotnetc/CMakeLists.txt

@@ -4,13 +4,13 @@ set( CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR} )
 file(TO_NATIVE_PATH "${CMAKE_RUNTIME_OUTPUT_DIRECTORY}" DOS_STYLE_OUTPUT_DIRECTORY)
 file(TO_NATIVE_PATH "${CMAKE_CURRENT_SOURCE_DIR}" DOS_STYLE_SOURCE_DIR)
 
-if (CMAKE_GENERATOR MATCHES "Visual Studio.*Win64" )
+if (DXC_BUILD_ARCH MATCHES "x64" )
   set ( DOTNET_PLATFORM_TARGET "x64" )
 elseif (CMAKE_GENERATOR STREQUAL "Visual Studio 12" )
   set ( DOTNET_PLATFORM_TARGET "x86" )
-else (CMAKE_GENERATOR MATCHES "Visual Studio.*Win64" )
+else (DXC_BUILD_ARCH MATCHES "x64" )
   set ( DOTNET_PLATFORM_TARGET "AnyCPU" )
-endif (CMAKE_GENERATOR MATCHES "Visual Studio.*Win64" )
+endif (DXC_BUILD_ARCH MATCHES "x64" )
 
 configure_file(dndxc.csproj.txt dndxc.csproj)
 

tools/clang/tools/dotnetc/EditorForm.Designer.cs

@@ -621,6 +621,8 @@ namespace MainNs
             "ps_6_1",
             "ps_6_2",
             "ps_6_3",
+            "ps_6_4",
+            "ps_6_5",
             "vs_6_0",
             "vs_6_1",
             "vs_6_2",
@@ -629,21 +631,31 @@ namespace MainNs
             "cs_6_1",
             "cs_6_2",
             "cs_6_3",
+            "cs_6_4",
+            "cs_6_5",
             "gs_6_0",
             "gs_6_1",
             "gs_6_2",
             "gs_6_3",
+            "gs_6_4",
+            "gs_6_5",
             "hs_6_0",
             "hs_6_1",
             "hs_6_2",
             "hs_6_3",
+            "hs_6_4",
+            "hs_6_5",
             "ds_6_0",
             "ds_6_1",
             "ds_6_2",
             "ds_6_3",
+            "ds_6_4",
+            "ds_6_5",
             "lib_6_1",
             "lib_6_2",
-            "lib_6_3"});
+            "lib_6_3",
+            "lib_6_4",
+            "lib_6_5"});
             this.cbProfile.Location = new System.Drawing.Point(6, 69);
             this.cbProfile.Name = "cbProfile";
             this.cbProfile.Size = new System.Drawing.Size(151, 28);