Revert "[cmake] Use `GNUInstallDirs` to support custom installation dirs."

Sorry for the disruption, I will try again later.

This reverts commit efeb50197091b2ade24c00b9d55814bc433a7fd1.

GitOrigin-RevId: 6e52bfe09d3ab3ae6c43c079d06ebeb7bb241dec
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6b3bcef..b738043 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,8 +10,6 @@
 
 cmake_minimum_required(VERSION 3.13.4)
 
-include(GNUInstallDirs)
-
 set(LLVM_COMMON_CMAKE_UTILS "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")
 
 # Add path for custom modules
@@ -212,7 +210,7 @@
   ${CMAKE_MODULE_PATH}
   )
 
-set(LIBCXXABI_INSTALL_RUNTIME_DIR "${CMAKE_INSTALL_BINDIR}" CACHE PATH
+set(LIBCXXABI_INSTALL_RUNTIME_DIR bin CACHE PATH
     "Path where built libc++abi runtime libraries should be installed.")
 
 if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)