Incorrect include paths for native x32


Building LLVM in a native x32 currently fails because the include
paths that LLVM is searching for header files is incomplete [1]:

bin/clang++ -c $CFLAGS -std=c++11 ../compiler-rt/lib/fuzzer/*.cpp -IFuzzer; \
ar ruv libFuzzer.a Fuzzer*.o
-g -O2 -fdebug-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2
In file included from ../compiler-rt/lib/fuzzer/FuzzerClangCounters.cpp:22:
../compiler-rt/lib/fuzzer/FuzzerDefs.h:15:10: fatal error: 'cassert' file not found
#include <cassert>

There is an open changeset by James Clarke to address this issue. Is
there any chance this can get a review?