Avoid exporting panic_unwind as stdlib cargo feature

There is already panic-unwind to enable it.

library/std/Cargo.toml

@@ -93,7 +93,7 @@ backtrace = [
     'miniz_oxide/rustc-dep-of-std',
 ]
 
-panic-unwind = ["panic_unwind"]
+panic-unwind = ["dep:panic_unwind"]
 compiler-builtins-c = ["alloc/compiler-builtins-c"]
 compiler-builtins-mem = ["alloc/compiler-builtins-mem"]
 compiler-builtins-no-asm = ["alloc/compiler-builtins-no-asm"]

library/sysroot/Cargo.toml

@@ -26,7 +26,7 @@ debug_typeid = ["std/debug_typeid"]
 llvm-libunwind = ["std/llvm-libunwind"]
 system-llvm-libunwind = ["std/system-llvm-libunwind"]
 optimize_for_size = ["std/optimize_for_size"]
-panic-unwind = ["std/panic_unwind"]
+panic-unwind = ["std/panic-unwind"]
 panic_immediate_abort = ["std/panic_immediate_abort"]
 profiler = ["dep:profiler_builtins"]
 std_detect_file_io = ["std/std_detect_file_io"]

src/tools/miri/cargo-miri/src/setup.rs

@@ -83,7 +83,7 @@ pub fn setup(
         SysrootConfig::NoStd
     } else {
         SysrootConfig::WithStd {
-            std_features: ["panic_unwind", "backtrace"].into_iter().map(Into::into).collect(),
+            std_features: ["panic-unwind", "backtrace"].into_iter().map(Into::into).collect(),
         }
     };
     let cargo_cmd = {