elf: Add tests for the dl hash funcs (_dl_new_hash and _dl_elf_hash)

If we want to further optimize the functions tests are needed.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

elf/simple-dl-hash.h

@@ -0,0 +1,42 @@
+/* __simple_dl_elf_hash for testing true elf symbol lookup.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _SIMPLE_DL_ELF_HASH_H
+#define _SIMPLE_DL_ELF_HASH_H 1
+
+#include <stdint.h>
+
+/* For testing/benchmarking purposes.  Real implementation in
+   sysdeps/generic/dl-hash.h.  */
+static uint32_t
+__attribute__ ((unused))
+__simple_dl_elf_hash (const char *name_arg)
+{
+  unsigned long int hash = 0;
+  for (unsigned char c = *name_arg; c != '\0'; c = *(++name_arg))
+    {
+      unsigned long int hi;
+      hash = (hash << 4) + c;
+      hi = hash & 0xf0000000;
+      hash ^= hi >> 24;
+      hash &= 0x0fffffff;
+    }
+  return hash;
+}
+
+#endif /* simple-dl-hash.h */