Add README for this.

README.md

@@ -0,0 +1,49 @@
+### nenolod's buildsys fork
+
+This is a custom version of [buildsys] (http://github.com/Midar/buildsys), designed for
+massively parallel builds.  The differences between official buildsys and this buildsys
+are:
+
+* A large amount of shell has been replaced with gmake builtin rule generation features.
+
+* You can use V=1 to get CFLAGS and LDFLAGS passed to commands.
+
+* Multiple `SUBDIRS` may be compiled in parallel.  This ensures that there are no stalls
+  in the build process on multi-core boxes.  If there is anything to build, we will be
+  building it.
+
+* Dependency generation is on a per-sourceunit basis and done entirely in parallel, including
+  across multiple `SUBDIRS`.  This speeds up builds by allowing dependency generation to
+  already be completed when you get deeper in the source tree.
+
+* The messages produced by the buildsystem have been changed so that V=1 output doesn't
+  look strange.
+
+Other than that, it is mostly compatible with official buildsys at an "API level."
+
+### Possible problems / FAQ
+
+#### I am getting notices about missing libraries that should be built already!
+
+The way we parallelize SUBDIRS is by converting each SUBDIR into a make task.  If a specific
+SUBDIR depends on another SUBDIR, you should denote it like so:
+
+```Make
+SUBDIRS = subdir1 subdir2 subdir3 subdir4
+
+# subdir2 depends on subdir1
+subdir2: subdir1
+
+# subdir3 depends on both subdir1 and subdir4
+subdir3: subdir2 subdir4
+```
+
+This results in subdir1 and subdir4 being built first, then subdir2 and subdir3
+respectively.
+
+#### It won't build my SUBDIRS.
+
+Put your SUBDIRS before your include lines.  You really are supposed to do this in
+buildsys *anyway*, but for some reason it sometimes lets you put it after the fact.
+
+My fork does not let you do that as SUBDIRS are turned into make tasks.