[libcxx] Stop using use c++ subdirectory for libc++ library

The new layout more closely matches the layout used by other compilers.
This is only used when LLVM_ENABLE_PER_TARGET_RUNTIME_DIR is enabled.

Differential Revision: https://reviews.llvm.org/D100869

GitOrigin-RevId: f749550cfe9f0bf2364abb2139835348587062ed
diff --git a/CMakeLists.txt b/CMakeLists.txt
index d54b1c5..d4eb01c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -195,8 +195,8 @@
 
 if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
   set(LIBCXXABI_HEADER_DIR ${LLVM_BINARY_DIR})
-  set(LIBCXXABI_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++)
-  set(LIBCXXABI_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++)
+  set(LIBCXXABI_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LLVM_DEFAULT_TARGET_TRIPLE})
+  set(LIBCXXABI_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE})
   if(LIBCXX_LIBDIR_SUBDIR)
     string(APPEND LIBCXXABI_LIBRARY_DIR /${LIBCXXABI_LIBDIR_SUBDIR})
     string(APPEND LIBCXXABI_INSTALL_LIBRARY_DIR /${LIBCXXABI_LIBDIR_SUBDIR})