[gcc(refs/users/iains/heads/d-for-darwin)] libphobos: Fix broken ucontext implementation, and other small test fixes

[Iain D Sandoe]

https://gcc.gnu.org/g:fdbfa9f9b5916a99687a9089851754cf98162119

commit fdbfa9f9b5916a99687a9089851754cf98162119
Author: Iain Buclaw <ibuclaw@gdcproject.org>
Date:   Wed Dec 9 10:49:34 2020 +0100

    libphobos: Fix broken ucontext implementation, and other small test fixes

Diff:
---
 libphobos/src/std/experimental/allocator/package.d | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libphobos/src/std/experimental/allocator/package.d b/libphobos/src/std/experimental/allocator/package.d
index 11c85474365..7c404070ffa 100644
--- a/libphobos/src/std/experimental/allocator/package.d
+++ b/libphobos/src/std/experimental/allocator/package.d
@@ -622,7 +622,8 @@ allocator can be cast to $(D shared).
 
     testAllocatorObject(processAllocator);
     testAllocatorObject(theAllocator);
-    assertThrown!AssertError(processAllocator = null);
+    // XBUG: Asserts are not thrown in release code, so is a pointless check.
+    //assertThrown!AssertError(processAllocator = null);
 
     // Restore initial processAllocator state
     processAllocator = oldProcessAllocator;