[libc++] Move the oss-fuzz script to libc++

Instead of having this script be part of the OSS-Fuzz repository, I think
it makes more sense to have it alongside the rest of the fuzzing targets
in libc++.

libcxx/test/libcxx/fuzzing/oss-fuzz.sh

@@ -0,0 +1,23 @@
+#!/bin/bash -eu
+
+#
+# This script runs the continuous fuzzing tests on OSS-Fuzz.
+#
+
+if [[ $SANITIZER = *undefined* ]]; then
+  CXXFLAGS="$CXXFLAGS -fsanitize=unsigned-integer-overflow -fsanitize-trap=unsigned-integer-overflow"
+fi
+
+for f in $(grep -v "#" libcxx/fuzzing/RoutineNames.txt); do
+  cat > ${f}_fuzzer.cc <<EOF
+#include "fuzzing/fuzzing.h"
+#include <cassert>
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+  int result = fuzzing::$f(data, size);
+  assert(result == 0); return 0;
+}
+EOF
+  $CXX $CXXFLAGS -std=c++11 ${f}_fuzzer.cc ./libcxx/fuzzing/fuzzing.cpp \
+      -nostdinc++ -cxx-isystem ./libcxx/include -iquote ./libcxx \
+      -o $OUT/$f $LIB_FUZZING_ENGINE
+done