Make musl-cross a normal Heads module.

This merges pull request #99 by @blackwellops and removes
the ./bootstrap script since the musl-cross can be built as
part of the normal dependency tree.

README.md

@@ -28,9 +28,7 @@ Building heads
 In order to build reproducible firmware images, Heads builds a specific
 version of gcc and uses it to compile the Linux kernel and various tools
 that go into the initrd.  Unfortunately this means the first step is a
-little slow...  After cloning the tree, cd into it and run `./bootstrap`
-to download and build binutils, gcc and all of their dependencies into
-`./crossgcc/`.
+little slow since it will clone the `musl-cross` tree and build gcc... 
 
 Once that is done, the top level `Makefile` will handle most of the
 remaining details -- it downloads the various packages, verifies the

modules/musl

@@ -27,4 +27,4 @@ musl_configure := ./configure \
 musl_target := -j 8 install
 #musl_target :=  install
 
-musl_depends := kernel-headers
+musl_depends := kernel-headers musl-cross

modules/musl-cross

@@ -0,0 +1,14 @@
+modules += musl-cross
+
+musl-cross_version := git
+musl-cross_dir := musl-cross-$(musl-cross_version)
+musl-cross_repo := https://github.com/GregorR/musl-cross
+
+musl-cross_output := $(pwd)/crossgcc/x86_64-linux-musl/bin/x86_64-linux-musl-gcc
+
+musl-cross_configure := \
+	echo > Makefile -n \
+	'$(musl-cross_output):\n\tCC_BASE_PREFIX="$(pwd)/crossgcc" ./build.sh'
+
+musl-cross_target :=
+