Cygwin 3.3 only: Replace SRWLOCK usage for malloc synchronization with
the first incarnation of the patch splitting malloc_init into two parts.
The SRWLOCK usage requires TryAcquireSRWLockExclusive, which isn't
available on Vista / Server 2008, unfortunately.
Per https://cygwin.com/pipermail/cygwin-developers/2021-October/012429.html,
we may encounter a crash when starting multiple threads during process
startup (here: fhandler_fifo::fixup_after_{fork,exec}) which in turn
allocate memory via malloc.
The problem is concurrent usage of malloc before the malloc muto has
been initialized.
To fix this issue, split malloc_init into malloc_init_0, called from
dll_crt0_0, and malloc_init_1, called from dll_crt_0_1. malloc_init_0
just initializes the muto, malloc_init_1 checks for user space provided
malloc.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
