Tweak build system to allow out-of-tree projects.

It's very annoying to have to build libmaple projects in-tree. Users
are just copying the repository everywhere. That's stupid. So I made this:

https://github.com/mbolivar/example-libmaple-project

It needs these patches to work.

Add a header and footer for rules.mk files, so we can change them
around and things will continue to work for the users, who just
include them.

In Makefile, add USER_MODULES to LIBMAPLE_MODULES if it's
nonempty. This is the hook you use to get your code compiled and
linked correctly.

Hack build-targets.mk for stupid reasons I hope to fix later. For now,
you'll need an empty main.cpp in BOTH the libmaple directory and your
directory if you want things to work the way you'd expect.

Signed-off-by: Marti Bolivar <mbolivar@leaflabs.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/support/make/header.mk b/support/make/header.mk
new file mode 100644
index 0000000..c85594a
--- /dev/null
+++ b/support/make/header.mk
@@ -0,0 +1,4 @@
+sp              := $(sp).x
+dirstack_$(sp)  := $(d)
+d               := $(dir)
+BUILDDIRS       += $(BUILD_PATH)/$(d)