Fix spurious toolchain warning

Author: codeinred

Matplot++Config.cmake.in

@@ -6,7 +6,7 @@ set(MATPLOT_BUILT_CXX_COMPILER_ID "@CMAKE_CXX_COMPILER_ID@")
 set(MATPLOT_BUILT_CXX_COMPILER_VERSION "@CMAKE_CXX_COMPILER_VERSION@")
 
 # Check if it matches the current toolchain
-if (NOT CMAKE_CXX_COMPILER_VERSION STREQUAL MATPLOT_BUILT_CXX_COMPILER_ID)
+if (NOT CMAKE_CXX_COMPILER_ID STREQUAL MATPLOT_BUILT_CXX_COMPILER_ID)
     message(WARNING "This installation of Matplot++ was built with ${MATPLOT_BUILT_CXX_COMPILER_ID}.")
 endif()