clang: multilib-header fix for llvm/Config/llvm-config.h and clang/Config/config.h

clang: multilib-header fix for llvm/Config/llvm-config.h and clang/Config/config.h

Error: Transaction test error:
  file /usr/include/clang/Config/config.h conflicts between attempted installs of
lib32-clang-dev-20.1.4-r0.core2_32 and clang-dev-20.1.4-r0.core2_64
  file /usr/include/llvm/Config/llvm-config.h conflicts between attempted
installs of lib32-clang-dev-20.1.4-r0.core2_32 and clang-dev-20.1.4-r0.core2_64

reproduce steps:
1. Add in local.conf the following lines:

  MACHINE ?= "qemux86-64"

  require conf/multilib.conf

  MULTILIBS ?= "multilib:lib32"

  DEFAULTTUNE:virtclass-multilib-lib32 ?= "core2-32"

2. add lib32-llvm-dev llvm-dev to core-image-minimal.bb

  IMAGE_INSTALL = "packagegroup-core-boot ${CORE_IMAGE_EXTRA_INSTALL} lib32-clang-dev clang-dev"

3. $ bitbake core-image-minimal

Signed-off-by: Liu Yiding <liuyd.fnst@fujitsu.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>