Don't impose unnecessary compile options on users

This is unexpected for users that take single job compilation as the
default (which is always the case since forever). Users can change the
default if they wish to use multicore for compilation.

cmake/Modules/MacroQbtCommonConfig.cmake

@@ -95,8 +95,4 @@ macro(qbt_common_config)
         set(CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")
     endif()
 
-    if (CMAKE_GENERATOR MATCHES "Visual Studio")
-        target_compile_options(qbt_common_cfg INTERFACE /MP)
-    endif()
-
 endmacro(qbt_common_config)