[KERNEL32][RTL] Diverse fixes/improvements for thread stack creation code. (#802)

- kernel32!BaseCreateStack() is compatible with ntdll!RtlpCreateUserStack().
- When checking whether a stack guard page can be added, its size has to
  be accounted for in the checking logic.
- We have to satisfy the PEB::MinimumStackCommit constraint.
- We cannot use PEB::GuaranteedStackBytes in BaseCreateStack() since it is
  nowhere initialized (default is 0). It gets initialized to a non-zero
  value when the user manually calls SetThreadStackGuarantee().
  https://www.installsetupconfig.com/win32programming/windowsthreadsprocessapis7_6.html

- RtlpCreateUserStack(): Fix memory leak in failure case.
- RtlpFreeUserStack() doesn't need to return anything.

See also commit 1bc59379 (r59868).

CORE-11319

dll/win32/kernel32/client/thread.c

@@ -165,9 +165,10 @@ CreateRemoteThread(IN HANDLE hProcess,
 
     /* Create the Stack */
     Status = BaseCreateStack(hProcess,
-                             dwStackSize,
-                             dwCreationFlags & STACK_SIZE_PARAM_IS_A_RESERVATION ?
-                             dwStackSize : 0,
+                             (dwCreationFlags & STACK_SIZE_PARAM_IS_A_RESERVATION) ?
+                                0 : dwStackSize,
+                             (dwCreationFlags & STACK_SIZE_PARAM_IS_A_RESERVATION) ?
+                                dwStackSize : 0,
                              &InitialTeb);
     if (!NT_SUCCESS(Status))
     {