[CMake] Add a specific 'install-clang-headers' target.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@253636 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Headers/CMakeLists.txt b/lib/Headers/CMakeLists.txt
index 3de7874..8c06b27 100644
--- a/lib/Headers/CMakeLists.txt
+++ b/lib/Headers/CMakeLists.txt
@@ -101,5 +101,14 @@
 
 install(
   FILES ${files} ${CMAKE_CURRENT_BINARY_DIR}/arm_neon.h
+  COMPONENT clang-headers
   PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
   DESTINATION lib${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION}/include)
+
+if (NOT CMAKE_CONFIGURATION_TYPES) # don't add this for IDE's.
+  add_custom_target(install-clang-headers
+    DEPENDS
+    COMMAND "${CMAKE_COMMAND}"
+            -DCMAKE_INSTALL_COMPONENT=clang-headers
+            -P "${CMAKE_BINARY_DIR}/cmake_install.cmake")
+endif()