Don't use C++11/14 flags when compiling with MSVC

Author: Sean L

CMakeLists.txt

@@ -24,10 +24,12 @@ if(WITH_STATIC)
 endif()
 add_library(docopt SHARED ${DOCOPT_SRC})
 
-if(WITH_CPP14)
-    add_definitions("-std=c++14")
-elseif(WITH_CPP11)
-    add_definitions("-std=c++11")
+if (NOT MSVC)
+    if(WITH_CPP14)
+        add_definitions("-std=c++14")
+    elseif(WITH_CPP11)
+        add_definitions("-std=c++11")
+    endif()
 endif()
 
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