[NFC][compiler-rt] Add missing header include (llvm#113951)

Include `cstdlib` which was originally included transitively but the
changes to `vector` in libcpp breaks new builds due to missing cstdlib
header for `abort()` function call.

Author: Prabhuk

compiler-rt/include/fuzzer/FuzzedDataProvider.h

@@ -18,6 +18,7 @@
 #include <climits>
 #include <cstddef>
 #include <cstdint>
+#include <cstdlib>
 #include <cstring>
 #include <initializer_list>
 #include <limits>