bpo-33164: blake2 fix for HP-UX (GH-13633)

Modules/_blake2/impl/blake2-impl.h

@@ -140,6 +140,9 @@ static inline void secure_zero_memory(void *v, size_t n)
 {
 #if defined(_WIN32) || defined(WIN32)
   SecureZeroMemory(v, n);
+#elif defined(__hpux)
+  static void *(*const volatile memset_v)(void *, int, size_t) = &memset;
+  memset_v(v, 0, n);
 #else
 // prioritize first the general C11 call
 #if defined(HAVE_MEMSET_S)

configure.ac

@@ -3527,6 +3527,8 @@ AC_CHECK_FUNCS(alarm accept4 setitimer getitimer bind_textdomain_codeset chown \
  getgrouplist getgroups getlogin getloadavg getpeername getpgid getpid \
  getpriority getresuid getresgid getpwent getpwnam_r getpwuid_r getspnam getspent getsid getwd \
  if_nameindex \
+ initgroups kill killpg lchmod lchown lockf linkat lstat lutimes mmap \
+ memrchr mbrtowc mkdirat mkfifo \
  madvise mkfifoat mknod mknodat mktime mremap nice openat pathconf pause pipe2 plock poll \
  posix_fallocate posix_fadvise posix_spawn posix_spawnp pread preadv preadv2 \
  pthread_condattr_setclock pthread_init pthread_kill putenv pwrite pwritev pwritev2 \