rustc-1.56.1-0: Update bootstrap paths

[Rust’s build system is unable to cope with our wrappers.][1]

    error: process didn't exit successfully: `/pkg/rustc-1.52.1-0/bin/rustc -vV` (exit code: 127)
    --- stderr
    /pkg/rustc-1.52.1-0/bin/rustc: error while loading shared libraries: librustc_driver-671169f26ffb48e3.so: cannot open shared object file: No such file or directory

Work around it it by setting the environment variables manually.

[1]: https://github.com/rust-lang/rust/issues/90562

rustc-1.56.1-0.build.sh

@@ -50,9 +50,9 @@ targets = "X86"
 experimental-targets = ""
 
 [build]
-cargo = "/usr/local/package/bin/cargo"
-rustc = "/usr/local/package/bin/rustc"
-rustfmt = "/usr/local/package/bin/rustfmt"
+cargo = "/pkg/rustc-1.52.1-0/bin/cargo"
+rustc = "/pkg/rustc-1.52.1-0/bin/rustc"
+rustfmt = "/pkg/rustc-1.52.1-0/bin/rustfmt"
 
 # omit HTML docs to save time and space (comment this to build them)
 docs = false
@@ -81,7 +81,7 @@ backtrace-on-ice = false
 
 EOF
 
-export RUSTFLAGS="$RUSTFLAGS -C link-args=-lffi" &&
+export PATH=/pkg/rustc-1.52.1-0/bin:$PATH LD_LIBRARY_PATH=/pkg/rustc-1.52.1-0/lib:$LD_LIBRARY_PATH RUSTFLAGS="$RUSTFLAGS -C link-args=-lffi"  &&
 python3 ./x.py build --exclude src/tools/miri
 
 python3 ./x.py install