[libc++] Fix incorrect install component for the libc++ linker script (#171663)

This patch fixes the name of the install component for the libc++ linker
script. Every other target mentions the cxx component, and that one
mentions libcxx. I believe that was a typo in 4bd3d16.

Author: ldionne

libcxx/src/CMakeLists.txt

@@ -381,7 +381,7 @@ endif()
 if (LIBCXX_ENABLE_SHARED AND LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
   install(FILES "$<TARGET_LINKER_FILE:cxx_shared>"
     DESTINATION ${LIBCXX_INSTALL_LIBRARY_DIR}
-    COMPONENT libcxx)
+    COMPONENT cxx)
 endif()
 
 if (NOT CMAKE_CONFIGURATION_TYPES)