```cmake
# Copyright 2017 gRPC authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

option(gRPC_MSVC_STATIC_RUNTIME "Link with static msvc runtime libraries" OFF)

if(gRPC_MSVC_STATIC_RUNTIME)
  # switch from dynamic to static linking of msvcrt
  foreach(flag_var
    CMAKE_C_FLAGS CMAKE_C_FLAGS_DEBUG CMAKE_C_FLAGS_RELEASE
    CMAKE_C_FLAGS_MINSIZEREL CMAKE_C_FLAGS_RELWITHDEBINFO
    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()
  endforeach()
endif()

```

Fix regression in MSVC runtime flag
user
```cmake
# Copyright 2017 gRPC authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

option(gRPC_MSVC_STATIC_RUNTIME "Link with static msvc runtime libraries" OFF)

if(gRPC_MSVC_STATIC_RUNTIME)
  # switch from dynamic to static linking of msvcrt
  foreach(flag_var
    CMAKE_C_FLAGS CMAKE_C_FLAGS_DEBUG CMAKE_C_FLAGS_RELEASE
    CMAKE_C_FLAGS_MINSIZEREL CMAKE_C_FLAGS_RELWITHDEBINFO
    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()
  endforeach()
endif()

```
assistant