[gn build] try to fix clang build after 37c030f

37c030f made it so that depending on //libcxx/include
automatically added the copied header dir to the include search path.
For some reason, clang can't build against the copied libcxx headers
(it complains about ldiv_t not being a type). I don't have a mac
to debug right now, but for the clang target this change was
unintentional anyways -- only depend on the copies target, instead
of on the target that also adjusts the include path.

llvm/utils/gn/secondary/clang/tools/driver/BUILD.gn

@@ -86,7 +86,7 @@ executable("clang") {
     # clang.  This is different from the CMake build, which requires devs to
     # explicitly build the "libcxx" target (which also needlessly compiles the
     # libcxx sources) to get a working compiler.
-    deps += [ "//libcxx/include" ]
+    deps += [ "//libcxx/include:copy_headers" ]
   }
   sources = [
     "cc1_main.cpp",

llvm/utils/gn/secondary/libcxx/include/BUILD.gn

@@ -217,7 +217,7 @@ if (current_toolchain == default_toolchain) {
       "wchar.h",
       "wctype.h",
     ]
-    deps = []
+    deps = [ ":write_config_site" ]
     if (target_os != "mac" && target_os != "win") {
       # libcxx/cmake/Modules/HandleLibCXXABI.cmake sets
       # LIBCXX_CXX_ABI_HEADER_TARGET if the libcxx abi library either of
@@ -264,7 +264,6 @@ config("include_config") {
 group("include") {
   deps = [
     ":copy_headers($default_toolchain)",
-    ":write_config_site($default_toolchain)",
   ]
   public_configs = [ ":include_config" ]
 }