Signed-off-by: Alexandre Julliard <julliard@winehq.org>

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=53783

This moves unsafe_block_from_ptr calls outside of the heap lock.

We assume here that concurrent call to another heap function on a block
being freed is undefined, and it should then be safe to do so:

* The block type or base offset never change after a block has been
  allocated and until it is freed.

* Block flags such as BLOCK_FLAG_LARGE, or BLOCK_FLAG_USER_INFO also
  never change after a block has been allocated.

* Other block flags are only read and modified inside the heap lock.

It's needed before is_inside_syscall accesses TEB.

We can't use NtCurrentTeb before setting %fs base.

Signed-off-by: Eric Pouech <eric.pouech@gmail.com>

This is used by clang to distinguish between MSVC and windows-itanium
targets. We override default option (usually meant for native builds)
to make sure that we use the right target.

-nostartfiles is not enough if clang is configured with explicit default rtlib.

-nostartfiles is not enough if clang is configured with explicit default rtlib.