Include clang in the ChromeOS toolchain tarball - part II.

This CL installs clang binaries into ${prefix}/usr/bin, instead of
${prefix}/bin, to which all other tools are installed. The rationale for
this is there is a close correlation between clang installation path and
the libraries / inclusion search path.

TEST=install the generated packages in simple chrome
BUG=chromiumo:587960

Change-Id: I2da16edd6bb0fc3e5be2dc900293e838f1121000
Reviewed-on: https://chromium-review.googlesource.com/329994
Commit-Ready: Han Shen <shenhan@chromium.org>
Tested-by: Han Shen <shenhan@chromium.org>
Reviewed-by: Luis Lozano <llozano@chromium.org>
diff --git a/scripts/cros_setup_toolchains.py b/scripts/cros_setup_toolchains.py
index 15c58fc..4590831 100644
--- a/scripts/cros_setup_toolchains.py
+++ b/scripts/cros_setup_toolchains.py
@@ -1029,8 +1029,14 @@
   # Link in all the package's files, any ELF dependencies, and wrap any
   # executable ELFs with helper scripts.
   def MoveUsrBinToBin(path):
-    """Move /usr/bin to /bin so people can just use that toplevel dir"""
-    return path[4:] if path.startswith('/usr/bin/') else path
+    """Move /usr/bin to /bin so people can just use that toplevel dir
+
+    Note we do not apply this to clang - there is correlation between clang's
+    search path for libraries / inclusion and its installation path.
+    """
+    if path.startswith('/usr/bin/') and path.find('clang') == -1:
+      return path[4:]
+    return path
   _BuildInitialPackageRoot(output_dir, paths, elfs, ldpaths,
                            path_rewrite_func=MoveUsrBinToBin, root=root)