[Fuzzer] Fix function prototype in fuzzer::ExternalFunctions. [NFC]

The __sanitizer_acquire_crash_state function has int return type, but the
fuzzer's external function definitions give it bool.

Places where __sanitizer_acquire_crash_state is declared:

  include/sanitizer_common/sanitizer_interface_defs.h
  lib/sanitizer_common/sanitizer_interface_internal.h
  lib/sanitizer_common/sanitizer_common.cc
  lib/fuzzer/FuzzerExtFunctions.def (this is the only bool)

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@353596 91177308-0d34-0410-b5e6-96231b3b80d8

Author: dlj

FuzzerExtFunctions.def

@@ -28,7 +28,7 @@ EXT_FUNC(LLVMFuzzerCustomCrossOver, size_t,
 EXT_FUNC(__lsan_enable, void, (), false);
 EXT_FUNC(__lsan_disable, void, (), false);
 EXT_FUNC(__lsan_do_recoverable_leak_check, int, (), false);
-EXT_FUNC(__sanitizer_acquire_crash_state, bool, (), true);
+EXT_FUNC(__sanitizer_acquire_crash_state, int, (), true);
 EXT_FUNC(__sanitizer_install_malloc_and_free_hooks, int,
          (void (*malloc_hook)(const volatile void *, size_t),
           void (*free_hook)(const volatile void *)),