build: Import gnu-efi as a submodule and build against it

Shim is rather more friendly with EFI internals than most code, and as a
result can end up making assumptions that are out of step with those made
by gnu-efi. Since both projects are developed independently, and since
distributions are often trying to build versions of shim against whatever
version of gnu-efi they are shipping, this can result in awkward build
failures. The easiest way to handle this is to use a git submodule and
import a known-good version of shim directly into the build tree. Given
static linking, this will also make reproducible builds easier.

Plus some changes from pjones:
- Fix up some more include paths
- more fine grained clean rules
- use our make ARCH
- use an rhboot/ repo for the gnu-efi remote

Signed-off-by: Matthew Garrett <mjg59@google.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 00000000..2ad8bb84
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,4 @@
+[submodule "gnu-efi"]
+	path = gnu-efi
+	url = https://github.com/rhboot/gnu-efi.git
+	branch = shim-15.3