Clang package: build with -DLIBCXX_ENABLE_{SHARED,STATIC}=OFF

After 61e89737, libc++ no longer supports linking against the system libc++abi.
We never cared about linking the library anyway, we just want the headers.
This lets us do that; see bug for discussion.

Bug: 1067216
Change-Id: Ib6265cf9c6c58d25e72f8f43ae994d9ec6da69a3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2133967Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Auto-Submit: Hans Wennborg <hans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756240}

tools/clang/scripts/build.py

@@ -473,6 +473,13 @@ def main():
       '-DLLVM_INCLUDE_GO_TESTS=OFF',
   ]
 
+  if sys.platform == 'darwin':
+    # For libc++, we only want the headers.
+    base_cmake_args.extend([
+        '-DLIBCXX_ENABLE_SHARED=OFF', '-DLIBCXX_ENABLE_STATIC=OFF',
+        '-DLIBCXX_INCLUDE_TESTS=OFF'
+    ])
+
   if args.gcc_toolchain:
     # Don't use the custom gcc toolchain when building compiler-rt tests; those
     # tests are built with the just-built Clang, and target both i386 and x86_64
@@ -489,12 +496,6 @@ def main():
     cxxflags.append('-I' + zlib_dir)
     ldflags.append('-LIBPATH:' + zlib_dir)
 
-  if sys.platform == 'darwin':
-    # Use the system libc++abi.
-    # TODO(hans): use https://reviews.llvm.org/D62060 instead
-    base_cmake_args.append('-DLIBCXX_CXX_ABI=libcxxabi')
-    base_cmake_args.append('-DLIBCXX_CXX_ABI_SYSTEM=1')
-
   if sys.platform != 'win32':
     # libxml2 is required by the Win manifest merging tool used in cross-builds.
     base_cmake_args.append('-DLLVM_ENABLE_LIBXML2=FORCE_ON')