[CMake] Support building Fuchsia toolchain on Darwin

This is already supported on Linux but on Darwin it requires some
extra flags.

Differential Revision: https://reviews.llvm.org/D30958

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@300257 91177308-0d34-0410-b5e6-96231b3b80d8

Author: petrhosek

cmake/caches/Fuchsia-stage2.cmake

@@ -19,6 +19,10 @@ if(NOT APPLE)
   set(CLANG_DEFAULT_LINKER lld CACHE STRING "")
 endif()
 
+if(APPLE)
+  set(LLDB_CODESIGN_IDENTITY "" CACHE STRING "")
+endif()
+
 set(CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING "")
 set(CMAKE_C_FLAGS_RELWITHDEBINFO "-O2 -gline-tables-only -DNDEBUG" CACHE STRING "")
 set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -gline-tables-only -DNDEBUG" CACHE STRING "")

cmake/caches/Fuchsia.cmake

@@ -19,6 +19,12 @@ if(NOT APPLE)
   set(BOOTSTRAP_LLVM_ENABLE_LLD ON CACHE BOOL "")
 endif()
 
+if(APPLE)
+  set(COMPILER_RT_ENABLE_IOS OFF CACHE BOOL "")
+  set(COMPILER_RT_ENABLE_TVOS OFF CACHE BOOL "")
+  set(COMPILER_RT_ENABLE_WATCHOS OFF CACHE BOOL "")
+endif()
+
 set(CLANG_BOOTSTRAP_TARGETS
   check-all
   check-llvm