Attempt to override broken buildbot config for libc++abi.

The buildbots were changed to pass -DLIBCXX_CXX_ABI=libcxxabi, but
they don't provide an include path for the library, so cxxabi.h is
never found while building libc++.

This is a temporary change until the buildbots are updated or until
D63883 lands in a form that unbreaks the bots

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@365847 91177308-0d34-0410-b5e6-96231b3b80d8

CMakeLists.txt

@@ -147,6 +147,14 @@ 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"))
+    message(WARNING "OVERRIDING BUILDBOT CONFIG")
+    set(LIBCXX_CXX_ABI "default" CACHE STRING "FIXME" FORCE)
+  endif()
+endif()
 # Setup the default options if LIBCXX_CXX_ABI is not specified.
 if (LIBCXX_CXX_ABI STREQUAL "default")
   find_path(