Import v1.3.1 vendor code.
Merge branch 'vendor' to get 1.3.1 code.

Conflicts:
	osdep.c
Guard O_ASYNC with an #ifdef as done for other flags.

Haiku does not provide O_ASYNC (yet).
Expose pixman CFLAGS separately and use for C++ files.

Fixes the build of the Haiku GUI wrt. include dependencies.
Fix cast to match return type to avoid warning.
Update Haiku GUI to use new display hook names.
Import v1.4.2 vendor code.
Merge branch 'vendor' to get 1.4.2 code.

Conflicts:
	block/raw-posix.c
Adjust to new include path and remove now redundant declaration.