[libc++] Remove workaround for D63883

I tried applying D63883 three times and could never get around to
making it work. I'm giving up on that for now, but soon this should
be irrelevant anyway since all builds will move to the monorepo
(where we're always using the in-tree libc++abi unless explicitly
specified otherwise).

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@373384 91177308-0d34-0410-b5e6-96231b3b80d8

CMakeLists.txt

@@ -148,16 +148,6 @@ set(LIBCXX_CXX_ABI "default" CACHE STRING
 set(CXXABIS none default libcxxabi libcxxrt libstdc++ libsupc++ vcruntime)
 set_property(CACHE LIBCXX_CXX_ABI PROPERTY STRINGS ;${CXXABIS})
 
-# FIXME: This is a temporary hack to get the buildbots working while D63883 is in flight.
-# Without this all the bots fail while building libc++
-if (DEFINED ENV{USER})
-  if (("$ENV{USER}" STREQUAL "buildbot") OR (("$ENV{USER}" STREQUAL "llvmbb") OR ("$ENV{USER}" STREQUAL "buildslave")))
-    if (LIBCXX_CXX_ABI STREQUAL "libcxxabi" AND NOT DEFINED LIBCXX_CXX_ABI_INCLUDE_PATHS)
-      message(WARNING "OVERRIDING BUILDBOT CONFIG")
-      set(LIBCXX_CXX_ABI "default" CACHE STRING "FIXME" FORCE)
-    endif()
-  endif()
-endif()
 # Setup the default options if LIBCXX_CXX_ABI is not specified.
 if (LIBCXX_CXX_ABI STREQUAL "default")
   find_path(