Update to shim 15.4

- Shim now uses submodules, so run `git submodule update --init` after
  cloning the repo
- The build patch is no longer needed, drop that
- Update the container to the latest fedora release (28 -> 33)

Dockerfile

diff --git a/Dockerfile b/Dockerfile
index 3c9f689..3ae6b7c 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM fedora:28
+FROM fedora:33
 
 RUN dnf install -y \
     gcc \
@@ -7,13 +7,10 @@
     make \
     patch
 
-# Clone shim, check out tag shim-15.1
-RUN git clone --branch shim-15.1 https://github.com/rhboot/shim.git /build/shim
+# Clone shim, check out tag 15.4, and init submodules
+RUN git clone --branch 15.4 https://github.com/rhboot/shim.git /build/shim
 WORKDIR /build/shim
-
-# Apply a patch to fix compilation
-ADD build-fix.patch .
-RUN patch -p1 -i build-fix.patch
+RUN git submodule update --init
 
 # Add our public certificate
 ADD neverware.cer .

build-fix.patch

diff --git a/build-fix.patch b/build-fix.patch
deleted file mode 100644
index 59898a5..0000000
--- a/build-fix.patch
+++ /dev/null
@@ -1,12 +0,0 @@
-diff --git a/mok.c b/mok.c
-index 2216e98..afee969 100644
---- a/mok.c
-+++ b/mok.c
-@@ -323,6 +323,7 @@ maybe_mirror_one_mok_variable(struct mok_state_variable *v, EFI_STATUS ret)
- 				ret = efi_status;
- 			perror(L"Could not create %s: %r\n", v->rtname,
- 			       efi_status);
-+		}
- 	}
- 	return ret;
- }