fix: lower cmake version to 3.7

Author: natiz

packages/grpc-tools/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.15)
+cmake_minimum_required(VERSION 3.7)
 if(COMMAND cmake_policy)
   cmake_policy(SET CMP0003 NEW)
 endif(COMMAND cmake_policy)
@@ -26,8 +26,21 @@ add_executable(grpc_node_plugin
 )
 
 if (MSVC)
-  set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreaded$<$<CONFIG:Debug>:Debug>)
-endif (MSVC)
+  if (CMAKE_VERSION VERSION_GREATER_EQUAL 3.15)
+      set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreaded$<$<CONFIG:Debug>:Debug>)
+  else ()
+    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 ()
+endif (MVC)
 
 target_include_directories(grpc_node_plugin
   PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}