Rework OS abstractions

- As much as possible avoid dragging system headers into translation
  units. This should avoid namespace pollution and, hopefully, speed up
  builds a little bit.

- Avoid leaning on the UCRT so much on Windows - prefer native win32
  calls and native file handles except where doing so is inconvenient
  (in particular, for stat(), which we might try and replace later).

- Also, switch from SystemFunction036 to ProcessPrng on Windows. This
  requires us to generate a stub for bcryptprimitives.dll because
  Microsoft haven't bothered to provide a link library, but the function
  is better-documented and seems to be a more direct under-the-hood call
  as well. Apparently it's what's used by the major web browsers these
  days, which seems like a good indication it's stable and trusted.

- Lastly, remove a bunch of functions and macros and stuff that weren't
  actually being used. It seems good to try and keep the scope of
  OS-dependent stuff relatively contained and only add to it when
  actually required.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/build/skiplist.h b/src/build/skiplist.h
index b747d89..ab6a920 100644
--- a/src/build/skiplist.h
+++ b/src/build/skiplist.h
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2022 Michael Smith <mikesmiffy128@gmail.com>
+ * Copyright © 2024 Michael Smith <mikesmiffy128@gmail.com>
  *
  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -24,6 +24,7 @@
 
 #ifdef _WIN32
 static inline int _skiplist_ffs(uint x) {
+	uchar _BitScanForward(ulong *idx, ulong mask);
 	uint ret;
 	// on Windows, sizeof(ulong) == sizeof(uint)
 	if (_BitScanForward((ulong *)&ret, x)) return ret + 1; else return 0;