Move libc++ and libc++abi to buildtools.

.DEPS.git

Index: .DEPS.git
diff --git a/.DEPS.git b/.DEPS.git
index b8100beb6e5c0167ee8355f9bdd3e0ef14871344..a76935848c9674128d4ea129be501dcf03da7a5e 100644
--- a/.DEPS.git
+++ b/.DEPS.git
@@ -8,10 +8,18 @@ vars = {
   "git_url": "https://chromium.googlesource.com",
 
   "clang_format_rev": "81edd558fea5dd7855d67a1dc61db34ae8c1fd63", # r223685
+  "libcxx_revision": "48198f9110397fff47fe7c37cbfa296be7d44d3d",
+  "libcxxabi_revision": "4ad1009ab3a59fa7a6896d74d5e4de5885697f95",
 }
 
 deps = {
   "clang_format/script":
       Var("git_url") + "/chromium/llvm-project/cfe/tools/clang-format.git@" +
       Var("clang_format_rev"),
+  "libc++/trunk":
+      Var("git_url") + "/chromium/llvm-project/libcxx.git" + "@" +
+      Var("libcxx_revision"),
+  "libc++abi/trunk":
+      Var("git_url") + "/chromium/llvm-project/libcxxabi.git" + "@" +
+      Var("libcxxabi_revision"),
 }