Make shared libraries be able to link to MSVC static runtime libraries, so that…

Make shared libraries be able to link to MSVC static runtime libraries, so that VC runtime is not required.

cmake/CMakeLists.txt

@@ -40,8 +40,6 @@ else (BUILD_SHARED_LIBS)
 endif (BUILD_SHARED_LIBS)
 option(protobuf_BUILD_SHARED_LIBS "Build Shared Libraries" ${protobuf_BUILD_SHARED_LIBS_DEFAULT})
 include(CMakeDependentOption)
-cmake_dependent_option(protobuf_MSVC_STATIC_RUNTIME "Link static runtime libraries" ON
-  "NOT protobuf_BUILD_SHARED_LIBS" OFF)
 set(protobuf_WITH_ZLIB_DEFAULT ON)
 option(protobuf_WITH_ZLIB "Build with zlib support" ${protobuf_WITH_ZLIB_DEFAULT})
 set(protobuf_DEBUG_POSTFIX "d"
@@ -155,22 +153,22 @@ if (protobuf_BUILD_SHARED_LIBS)
   set(protobuf_SHARED_OR_STATIC "SHARED")
 else (protobuf_BUILD_SHARED_LIBS)
   set(protobuf_SHARED_OR_STATIC "STATIC")
-  # In case we are building static libraries, link also the runtime library statically
-  # so that MSVCR*.DLL is not required at runtime.
-  # https://msdn.microsoft.com/en-us/library/2kzt1wy3.aspx
-  # This is achieved by replacing msvc option /MD with /MT and /MDd with /MTd
-  # http://www.cmake.org/Wiki/CMake_FAQ#How_can_I_build_my_MSVC_application_with_a_static_runtime.3F
-  if (MSVC AND protobuf_MSVC_STATIC_RUNTIME)
-    foreach(flag_var
-        CMAKE_CXX_FLAGS CMAKE_CXX_FLAGS_DEBUG CMAKE_CXX_FLAGS_RELEASE
-        CMAKE_CXX_FLAGS_MINSIZEREL CMAKE_CXX_FLAGS_RELWITHDEBINFO)
-      if(${flag_var} MATCHES "/MD")
-        string(REGEX REPLACE "/MD" "/MT" ${flag_var} "${${flag_var}}")
-      endif(${flag_var} MATCHES "/MD")
-    endforeach(flag_var)
-  endif (MSVC AND protobuf_MSVC_STATIC_RUNTIME)
 endif (protobuf_BUILD_SHARED_LIBS)
 
+# In case we are linking the runtime library statically so that MSVCR*.DLL is not required at runtime.
+# https://msdn.microsoft.com/en-us/library/2kzt1wy3.aspx
+# This is achieved by replacing msvc option /MD with /MT and /MDd with /MTd
+# http://www.cmake.org/Wiki/CMake_FAQ#How_can_I_build_my_MSVC_application_with_a_static_runtime.3F
+if (MSVC AND protobuf_MSVC_STATIC_RUNTIME)
+  foreach(flag_var
+      CMAKE_CXX_FLAGS CMAKE_CXX_FLAGS_DEBUG CMAKE_CXX_FLAGS_RELEASE
+      CMAKE_CXX_FLAGS_MINSIZEREL CMAKE_CXX_FLAGS_RELWITHDEBINFO)
+    if(${flag_var} MATCHES "/MD")
+      string(REGEX REPLACE "/MD" "/MT" ${flag_var} "${${flag_var}}")
+    endif(${flag_var} MATCHES "/MD")
+  endforeach(flag_var)
+endif (MSVC AND protobuf_MSVC_STATIC_RUNTIME)
+
 if (MSVC)
   # Build with multiple processes
   add_definitions(/MP)