Update Musl Libc code

We now have implement all of Musl's localization code, the same way that
Musl implements localization. You may need setlocale(LC_ALL, "C.UTF-8"),
just in case anything stops working as expected.

libc/thread/mktls.c

@@ -40,7 +40,6 @@ static char *_mktls_finish(struct CosmoTib **out_tib, char *mem,
   tib->tib_ftrace = old->tib_ftrace;
   tib->tib_strace = old->tib_strace;
   tib->tib_sigmask = old->tib_sigmask;
-  tib->tib_locale = (intptr_t)&__c_dot_utf8_locale;
   atomic_store_explicit(&tib->tib_tid, -1, memory_order_relaxed);
   if (out_tib) {
     *out_tib = tib;

libc/thread/posixthread.internal.h

@@ -69,6 +69,8 @@ enum PosixThreadStatus {
 
 #define POSIXTHREAD_CONTAINER(e) DLL_CONTAINER(struct PosixThread, list, e)
 
+typedef struct __locale_struct *locale_t;
+
 struct PosixThread {
   int pt_flags;            // 0x00: see PT_* constants
   atomic_int pt_canceled;  // 0x04: thread has bad beliefs
@@ -86,6 +88,7 @@ struct PosixThread {
   uint64_t pt_blkmask;
   int64_t pt_semaphore;
   intptr_t pt_iohandle;
+  locale_t pt_locale;
   void *pt_ioverlap;
   jmp_buf pt_exiter;
   pthread_attr_t pt_attr;

libc/thread/pthread_create.c

@@ -44,6 +44,7 @@
 #include "libc/runtime/runtime.h"
 #include "libc/runtime/stack.h"
 #include "libc/runtime/syslib.internal.h"
+#include "libc/str/locale.internal.h"
 #include "libc/str/str.h"
 #include "libc/sysv/consts/auxv.h"
 #include "libc/sysv/consts/clone.h"
@@ -235,6 +236,7 @@ static errno_t pthread_create_impl(pthread_t *thread,
     return EAGAIN;
   }
   dll_init(&pt->list);
+  pt->pt_locale = &__global_locale;
   pt->pt_start = start_routine;
   pt->pt_arg = arg;
 

libc/thread/tls.h

@@ -23,7 +23,7 @@ struct CosmoTib {
   struct CosmoTib *tib_self;      /* 0x00 */
   struct CosmoFtrace tib_ftracer; /* 0x08 */
   void *tib_garbages;             /* 0x18 */
-  intptr_t tib_locale;            /* 0x20 */
+  intptr_t __unused;              /* 0x20 */
   intptr_t tib_pthread;           /* 0x28 */
   struct CosmoTib *tib_self2;     /* 0x30 */
   _Atomic(int32_t) tib_tid;       /* 0x38 transitions -1 → tid → 0 */