regenerate CMakeLists.txt

CMakeLists.txt

@@ -40,6 +40,7 @@ set(gRPC_INSTALL_SHAREDIR "share/grpc" CACHE STRING "Installation directory for
 option(gRPC_BUILD_TESTS "Build tests" OFF)
 option(gRPC_BUILD_CODEGEN "Build codegen" ON)
 option(gRPC_BUILD_CSHARP_EXT "Build C# extensions" ON)
+option(gRPC_BACKWARDS_COMPATIBILITY_MODE "Build libraries that are binary compatible across a larger number of OS and libc versions" OFF)
 
 set(gRPC_INSTALL_default ON)
 if (NOT CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
@@ -115,6 +116,14 @@ else()
   set(_gRPC_PROTOBUF_LIBRARY_NAME "libprotobuf")
 endif()
 
+if(gRPC_BACKWARDS_COMPATIBILITY_MODE)
+  add_definitions(-DGPR_BACKWARDS_COMPATIBILITY_MODE)
+  if (_gRPC_PLATFORM_MAC)
+    # CMAKE_OSX_DEPLOYMENT_TARGET
+    add_definitions(-mmacosx-version-min=10.7)
+  endif()
+endif()
+
 if (_gRPC_PLATFORM_LINUX OR _gRPC_PLATFORM_MAC)
   # C core has C++ source code, but should not depend on libstc++ (for better portability).
   # We need to use a few tricks to convince cmake to do that.