[gcc(refs/users/acsawdey/heads/memcpy-unaligned-vsx)] libstdc++: Fix <stop_token> to compile without gthreads

[Aaron Sawdey]

https://gcc.gnu.org/g:35e5294c4b779f8fc24fdc86464f999867332995

commit 35e5294c4b779f8fc24fdc86464f999867332995
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Aug 11 16:16:21 2020 +0100

    libstdc++: Fix <stop_token> to compile without gthreads
    
    libstdc++-v3/ChangeLog:
    
            * include/std/stop_token: Check _GLIBCXX_HAS_GTHREADS using
            #ifdef instead of #if.
            (stop_token::_S_yield()): Check _GLIBCXX_HAS_GTHREADS before
            using __gthread_yield.

Diff:
---
 libstdc++-v3/include/std/stop_token | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/libstdc++-v3/include/std/stop_token b/libstdc++-v3/include/std/stop_token
index 847d12f7454..ccec6fab15c 100644
--- a/libstdc++-v3/include/std/stop_token
+++ b/libstdc++-v3/include/std/stop_token
@@ -105,7 +105,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     {
 #if defined __i386__ || defined __x86_64__
       __builtin_ia32_pause();
-#elif defined _GLIBCXX_USE_SCHED_YIELD
+#elif defined _GLIBCXX_HAS_GTHREADS && defined _GLIBCXX_USE_SCHED_YIELD
       __gthread_yield();
 #endif
     }
@@ -162,7 +162,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       std::atomic<value_type> _M_owners{1};
       std::atomic<value_type> _M_value{_S_ssrc_counter_inc};
       _Stop_cb* _M_head = nullptr;
-#if _GLIBCXX_HAS_GTHREADS
+#ifdef _GLIBCXX_HAS_GTHREADS
       __gthread_t _M_requester;
 #endif
 
@@ -237,7 +237,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  }
 	while (!_M_try_lock_and_stop(__old));
 
-#if _GLIBCXX_HAS_GTHREADS
+#ifdef _GLIBCXX_HAS_GTHREADS
 	_M_requester = __gthread_self();
 #endif
 
@@ -266,7 +266,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	    if (!__destroyed)
 	      {
 		__cb->_M_destroyed = nullptr;
-#if _GLIBCXX_HAS_GTHREADS
+#ifdef _GLIBCXX_HAS_GTHREADS
 		// synchronize with destructor of stop_callback that owns *__cb
 		__cb->_M_done.release();
 #endif
@@ -343,7 +343,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	// Callback is not in the list, so must have been removed by a call to
 	// _M_request_stop.
 
-#if _GLIBCXX_HAS_GTHREADS
+#ifdef _GLIBCXX_HAS_GTHREADS
 	// Despite appearances there is no data race on _M_requester. The only
 	// write to it happens before the callback is removed from the list,
 	// and removing it from the list happens before this read.