* gnu/packages/rust.scm (%mrustc-commit): Update to newest commit.
(%mrustc-source): Update to 0.11.0-1.5e01a76. Add a patch. Adjust the
snippet to not use vendored openssl.
(rust-bootstrap)[source]: Remove patch, remove patch-flags. Add to the
snippet a substitution for compatibility with llvm-13.
[inputs]: Remove input labels. Remove conditional use of clang.
[arguments]: Allow parallel building on all architectures. Update the
make-flags. Replace the 'unpack phase to unpack the mrustc sources.
Delete the custom 'set-mrustc-sources and 'patch-cargo-checksum phases.
Adjust the custom 'patch-makefiles phase. Adjust the 'configure and
'build phases to no longer use clang on some architectures.
* gnu/packages/patches/mrustc-patches.patch: New file.
* gnu/packages/patches/rustc-1.54.0-src.patch: Remove file.
* gnu/local.mk (dist_patch_DATA): Update it.
Change-Id: I7e444abe4b386b1bb77f05a278ddef45152ddb3c
