ww: import toolchain — C bootstrap + ww-side self-host (phases 0-10)

C bootstrap (phases 0-9):
  cmd/wwc, cmd/6c, cmd/6a, cmd/6l, cmd/ww, rt, lib/*.

ww-side self-host (phase 10):
  selfhost/cmd/wwc — ww-cgen frontend; bootstrap fixed point.
  selfhost/cmd/6a  — assembler; byte-identical to C 6a (test 991).
  selfhost/cmd/6l  — linker w/ archive (.a) support; byte-identical
                     to C 6l (test 992).
  selfhost/cmd/ww  — driver (build/run/version); byte-identical to
                     C ww (test 993).

make test: 15/15. make bootstrap: ww2.s == ww3.s, ww2.o == ww3.o,
ww2 == ww3 byte-identical, with the full ww-tooled chain.

lib/hash/fnv/fnv.ww

@@ -0,0 +1,15 @@
+// hash/fnv — FNV-1a 64-bit. Pure ww. No dependencies.
+
+def OFFSET: u64 = 14695981039346656037;
+def PRIME:  u64 = 1099511628211;
+
+export fn fnv1a(buf: []u8) u64 = {
+	let h: u64 = OFFSET;
+	let i: i32 = 0;
+	for (i < buf.len) {
+		h = h ^ (buf[i]: u64);
+		h = h * PRIME;
+		i += 1;
+	};
+	return h;
+};