refactor: drop the bfd TLS workaround, binutils uses real TLS now

With the TLS runtime landed (PT_TLS loading + per-thread FS base) and
tls-test.elf passing on the OS, the sysdep.h hunk that degraded BFD's
_Thread_local error state to plain globals is no longer needed.
Native binutils is rebuilt with genuine thread-locals: the shipped
tools now carry a PT_TLS segment and %fs-relative accesses, exercising
the new runtime in every invocation.

Co-Authored-By: Claude Fable 5 <[email protected]>

toolchain/patches/binutils-2.43.1-montauk.patch

@@ -45,21 +45,3 @@
  x86_64-*-elf* | x86_64-*-rtems* | x86_64-*-fuchsia* | x86_64-*-genode*)
  			targ_emul=elf_x86_64
  			targ_extra_emuls="elf_i386 elf_iamcu elf32_x86_64"
---- a/bfd/sysdep.h
-+++ b/bfd/sysdep.h
-@@ -27,6 +27,15 @@
- #endif
- 
- #include "config.h"
-+
-+/* MontaukOS provides no runtime TLS yet (no FS-base setup, no PT_TLS
-+   handling in the ELF loader), so a _Thread_local access traps at
-+   %fs:0. Degrade BFD's thread-local error state to plain globals;
-+   the native tools are single-threaded. */
-+#ifdef __montauk__
-+#undef TLS
-+#define TLS
-+#endif
- #include <stdio.h>
- 
- #ifdef HAVE_SYS_TYPES_H