Remove some legacy cruft

Function trace logs will report stack usage accurately. It won't include
the argv/environ block. Our clone() polyfill is now simpler and does not
use as much stack memory. Function call tracing on x86 is now faster too

libc/intrin/sig.c

@@ -89,14 +89,14 @@ __msabi extern typeof(WriteFile) *const __imp_WriteFile;
 
 extern pthread_mutex_t __sig_worker_lock;
 
-HAIRY static bool __sig_ignored_by_default(int sig) {
+textwindows static bool __sig_ignored_by_default(int sig) {
   return sig == SIGURG ||   //
          sig == SIGCONT ||  //
          sig == SIGCHLD ||  //
          sig == SIGWINCH;
 }
 
-HAIRY bool __sig_ignored(int sig) {
+textwindows bool __sig_ignored(int sig) {
   return __sighandrvas[sig] == (intptr_t)SIG_IGN ||
          (__sighandrvas[sig] == (intptr_t)SIG_DFL &&
           __sig_ignored_by_default(sig));
@@ -532,14 +532,14 @@ textwindows void __sig_generate(int sig, int sic) {
   }
 }
 
-HAIRY static char *__sig_stpcpy(char *d, const char *s) {
+textwindows static char *__sig_stpcpy(char *d, const char *s) {
   size_t i;
   for (i = 0;; ++i)
     if (!(d[i] = s[i]))
       return d + i;
 }
 
-HAIRY wontreturn static void __sig_death(int sig, const char *thing) {
+textwindows wontreturn static void __sig_death(int sig, const char *thing) {
 #ifndef TINY
   intptr_t hStderr;
   char sigbuf[21], s[128], *p;
@@ -810,7 +810,7 @@ HAIRY static uint32_t __sig_worker(void *arg) {
     _pthread_mutex_unlock(&__sig_worker_lock);
     Sleep(POLL_INTERVAL_MS);
   }
-  return 0;
+  __builtin_unreachable();
 }
 
 __attribute__((__constructor__(10))) textstartup void __sig_init(void) {

libc/intrin/sigproc.c

@@ -34,6 +34,8 @@
 #include "libc/nt/thunk/msabi.h"
 #ifdef __x86_64__
 
+#define ABI __msabi textwindows dontinstrument
+
 // cut back on code size and avoid setting errno
 // this code is a mandatory dependency of winmain
 __msabi extern typeof(CloseHandle) *const __imp_CloseHandle;
@@ -47,8 +49,8 @@ __msabi extern typeof(GetEnvironmentVariable)
     *const __imp_GetEnvironmentVariableW;
 
 // Generates C:\ProgramData\cosmo\sig\x\y.pid like path
-__msabi textwindows dontinstrument char16_t *__sig_process_path(
-    char16_t *path, uint32_t pid, int create_directories) {
+ABI char16_t *__sig_process_path(char16_t *path, uint32_t pid,
+                                 int create_directories) {
   char16_t buf[3];
   char16_t *p = path;
   uint32_t vlen = __imp_GetEnvironmentVariableW(u"SYSTEMDRIVE", buf, 3);
@@ -100,7 +102,7 @@ __msabi textwindows dontinstrument char16_t *__sig_process_path(
   return path;
 }
 
-__msabi textwindows atomic_ulong *__sig_map_process(int pid, int disposition) {
+ABI atomic_ulong *__sig_map_process(int pid, int disposition) {
   char16_t path[128];
   __sig_process_path(path, pid, disposition == kNtOpenAlways);
   intptr_t hand = __imp_CreateFileW(path, kNtGenericRead | kNtGenericWrite,

libc/intrin/sigprocmask-sysv.c

@@ -32,8 +32,7 @@ int sys_sigprocmask(int how, const sigset_t *opt_set,
         how, opt_set ? (sigset_t *)(intptr_t)(uint32_t)*opt_set : 0, 0, 0);
     rc = 0;
   }
-  if (rc != -1 && opt_out_oldset) {
+  if (rc != -1 && opt_out_oldset)
     *opt_out_oldset = old[0];
-  }
   return rc;
 }

libc/intrin/strsignal_r.c

@@ -36,12 +36,10 @@
 privileged const char *strsignal_r(int sig, char buf[21]) {
   char *p;
   const char *s;
-  if (!sig) {
+  if (!sig)
     return "0";
-  }
-  if ((s = GetMagnumStr(kSignalNames, sig))) {
+  if ((s = GetMagnumStr(kSignalNames, sig)))
     return s;
-  }
   if (SIGRTMIN <= sig && sig <= SIGRTMAX) {
     sig -= SIGRTMIN;
     buf[0] = 'S';

libc/intrin/ulock.c

@@ -79,7 +79,11 @@ int ulock_wait(uint32_t operation, void *addr, uint64_t value,
 //   it could also mean another thread calling ulock on this address was
 //   configured (via operation) in an inconsistent way.
 //
-int ulock_wake(uint32_t operation, void *addr, uint64_t wake_value) {
+// should be dontinstrument because SiliconThreadMain() calls this from
+// a stack managed by apple libc.
+//
+dontinstrument int ulock_wake(uint32_t operation, void *addr,
+                              uint64_t wake_value) {
   int rc;
   rc = __syscall3i(operation, (long)addr, wake_value, 0x2000000 | 516);
   LOCKTRACE("ulock_wake(%#x, %p, %lx) → %s", operation, addr, wake_value,