[openssl/openssl] 2da67a: issue-21718: remove setting of PTHREAD_MUTEX_NORMAL

[Neil Horman]

  Branch: refs/heads/openssl-3.1
  Home:   https://github.com/openssl/openssl
  Commit: 2da67ae1ce6b22a07d9eb8201ab7915475288c1f
      https://github.com/openssl/openssl/commit/2da67ae1ce6b22a07d9eb8201ab7915475288c1f
  Author: Neil Horman <nhorman at gmail.com>
  Date:   2023-08-17 (Thu, 17 Aug 2023)

  Changed paths:
    M crypto/threads_pthread.c

  Log Message:
  -----------
  issue-21718: remove setting of PTHREAD_MUTEX_NORMAL

issue: https://github.com/openssl/openssl/issues/21718

build break reported:
crypto/threads_pthread.c:76:5: warning: implicit declaration of function 'pthread_mutexattr_settype'; did you mean 'pthread_mutexattr_destroy'? [-Wimplicit-function-declaration]
   76 |     pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_NORMAL);
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~
      |     pthread_mutexattr_destroy
crypto/threads_pthread.c:76:38: error: 'PTHREAD_MUTEX_NORMAL' undeclared (first use in this function); did you mean 'PTHREAD_MUTEX_TIMED_NP'?
   76 |     pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_NORMAL);
      |                                      ^~~~~~~~~~~~~~~~~~~~
      |                                      PTHREAD_MUTEX_TIMED_NP

This occurs because PTHREAD_MUTEX_NORMAL is only defined in glibc if
__USE_UNIX98 or __USE_XOPEN2K8 is defined, which is derived from setting
__USE_POSIX_C_SOURCE or __XOPEN_SOURCE is selected in the glibc feature
set for a build.  Since openssl selects no specific feature set from
glibc, the build break occurs

We could select a feature set of course, but that seems like a
significant discussion to have prior to doing so. Instead, the simpler
solution is to just not set the mutex type at all, given that
pthread_mutexattr_init sets the default mutex type, which should be akin
to normal anyway (i.e. no mutex error checking or allowed-recursive
behavior)

Reviewed-by: Hugo Landau <hlandau at openssl.org>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21726)

(cherry picked from commit e4d808652b0a1a19cfe615a6659e65ead0245108)