set default compilation to c++ mode on msvc

Author: daanx

ide/vs2022/mimalloc-lib.vcxproj

@@ -308,7 +308,7 @@
       <WholeProgramOptimization>false</WholeProgramOptimization>
       <BufferSecurityCheck>false</BufferSecurityCheck>
       <InlineFunctionExpansion>Default</InlineFunctionExpansion>
-      <CompileAs>CompileAsC</CompileAs>
+      <CompileAs>CompileAsCpp</CompileAs>
       <IntrinsicFunctions>true</IntrinsicFunctions>
       <LanguageStandard>stdcpp20</LanguageStandard>
     </ClCompile>