build: Replace `make config` with a `./configure` script

This lets us do more traditional out-of-tree builds like

    $ ../path/to/bfs/configure
    $ make

The .mk files are moved from ./config to ./build, mostly so that
./configure will auto-complete easily.

1 files changed, 0 insertions, 10 deletions

diff --git a/config/has/pipe2.c b/config/has/pipe2.c
deleted file mode 100644
index 4cb43b5..0000000
--- a/config/has/pipe2.c
+++ /dev/null
@@ -1,10 +0,0 @@
-// Copyright © Tavian Barnes <tavianator@tavianator.com>
-// SPDX-License-Identifier: 0BSD
-
-#include <fcntl.h>
-#include <unistd.h>
-
-int main(void) {
-	int fds[2];
-	return pipe2(fds, O_CLOEXEC);
-}