cmake: Revert removal of runtime selection for legacy Windows builds

Author: PatTheMav

cmake/legacy.cmake

@@ -137,6 +137,12 @@ if(NOT OS_MACOS OR ENABLE_BROWSER_LEGACY)
 endif()
 
 if(OS_WINDOWS)
+  if(MSVC)
+    target_compile_options(obs-browser PRIVATE $<IF:$<CONFIG:DEBUG>,/MTd,/MT>)
+
+    target_compile_options(obs-browser-page PRIVATE $<IF:$<CONFIG:DEBUG>,/MTd,/MT>)
+  endif()
+
   target_link_libraries(obs-browser PRIVATE CEF::Library d3d11 dxgi)
 
   if(TARGET CEF::Wrapper_Debug)