allow windows users to choose dynamic runtime dll build

CMakeLists.txt

@@ -42,6 +42,11 @@ option(
 	"only lib"
 	OFF
 )
+option(
+    MSVC_RUNTIME_DLL
+    "use dynamic runtime /MD in msvc builds"
+	OFF
+)
 
 set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
@@ -66,8 +71,13 @@ if(USE_LLVM)
 endif()
 
 if(MSVC)
-	set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS} /MT /W4 /Oy /Ox /EHsc /GS- /Zi /DNDEBUG /DNOMINMAX")
-	set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS} /MTd /W4 /DNOMINMAX")
+    if(MSVC_RUNTIME_DLL)
+        set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS} /MD /W4 /Oy /Ox /EHsc /GS- /Zi /DNDEBUG /DNOMINMAX")
+        set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS} /MDd /W4 /DNOMINMAX")
+    else()
+    	set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS} /MT /W4 /Oy /Ox /EHsc /GS- /Zi /DNDEBUG /DNOMINMAX")
+	    set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS} /MTd /W4 /DNOMINMAX")
+    endif()
 	link_directories(${CMAKE_SOURCE_DIR}/../cybozulib_ext/lib)
 	link_directories(${CMAKE_SOURCE_DIR}/lib)
 else()