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, 20 insertions, 0 deletions

diff --git a/build/exports.mk b/build/exports.mk
new file mode 100644
index 0000000..ed19134
--- /dev/null
+++ b/build/exports.mk
@@ -0,0 +1,20 @@
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Makefile fragment that exports variables used by configuration scripts
+
+export XPREFIX=${PREFIX}
+export XMANDIR=${MANDIR}
+
+export XCC=${CC}
+export XINSTALL=${INSTALL}
+export XMKDIR=${MKDIR}
+export XPKG_CONFIG=${PKG_CONFIG}
+export XRM=${RM}
+
+export XCPPFLAGS=${CPPFLAGS}
+export XCFLAGS=${CFLAGS}
+export XLDFLAGS=${LDFLAGS}
+export XLDLIBS=${LDLIBS}
+
+export XNOLIBS=${NOLIBS}