Revert "fix(mux): fix proxying to unprefixed clang"

This is apparently not enough, as multiple LLVM tools are also not
prefixed with target tuple, thus a more complete approach is needed.

This reverts commit fa6ab62.

ruyi/mux/runtime.py

@@ -27,18 +27,14 @@ def mux_main(argv: List[str]) -> int | NoReturn:
     if basename == "ruyi-qemu":
         return mux_qemu_main(argv, vcfg)
 
-    is_unprefixed_clang = is_proxying_to_unprefixed_clang(basename)
     # match the basename with one of the configured target tuples
     target_tuple: str | None = None
     toolchain_bindir: str | None = None
     toolchain_sysroot: str | None = None
     gcc_install_dir: str | None = None
     for tgt_tuple, tgt_data in vcfg.targets.items():
         if not basename.startswith(f"{tgt_tuple}-"):
-            # Unprefixed Clang should be treated as having the "default"
-            # target tuple.
-            if not is_unprefixed_clang:
-                continue
+            continue
 
         log.D(f"matched target '{tgt_tuple}', data {tgt_data}")
         target_tuple = tgt_tuple
@@ -137,10 +133,6 @@ def is_proxying_to_clang(basename: str) -> bool:
     return "clang" in basename
 
 
-def is_proxying_to_unprefixed_clang(basename: str) -> bool:
-    return basename in ("clang", "clang++")
-
-
 def mux_qemu_main(argv: List[str], vcfg: RuyiVenvConfig) -> int | NoReturn:
     binpath = vcfg.qemu_bin
     if binpath is None: