Make fixes and improvements

- Introduce __assert_disable global
- Improve strsignal() thread safety
- Make system call tracing thread safe
- Fix SO_RCVTIMEO / SO_SNDTIMEO on Windows
- Refactor DescribeFoo() functions into one place
- Fix fork() on Windows when TLS and MAP_STACK exist
- Round upwards in setsockopt(SO_RCVTIMEO) on Windows
- Disable futexes on OpenBSD which seem extremely broken
- Implement a better kludge for monotonic time on Windows

libc/runtime/printmemoryintervals.c

@@ -17,6 +17,7 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/fmt/itoa.h"
+#include "libc/intrin/describeflags.internal.h"
 #include "libc/intrin/kprintf.h"
 #include "libc/macros.internal.h"
 #include "libc/runtime/memtrack.internal.h"
@@ -33,7 +34,7 @@ static bool IsNoteworthyHole(unsigned i, const struct MemoryIntervals *mm) {
 }
 
 void PrintMemoryIntervals(int fd, const struct MemoryIntervals *mm) {
-  char *p, mode[8];
+  char *p, mappingbuf[8], framebuf[32];
   long i, w, frames, maptally = 0, gaptally = 0;
   for (w = i = 0; i < mm->i; ++i) {
     w = MAX(w, LengthInt64Thousands(mm->p[i].y + 1 - mm->p[i].x));
@@ -42,8 +43,8 @@ void PrintMemoryIntervals(int fd, const struct MemoryIntervals *mm) {
     frames = mm->p[i].y + 1 - mm->p[i].x;
     maptally += frames;
     kprintf("%08x-%08x %s %'*ldx%s", mm->p[i].x, mm->p[i].y,
-            DescribeMapping(mm->p[i].prot, mm->p[i].flags, mode), w, frames,
-            DescribeFrame(mm->p[i].x));
+            (DescribeMapping)(mappingbuf, mm->p[i].prot, mm->p[i].flags), w,
+            frames, (DescribeFrame)(framebuf, mm->p[i].x));
     if (mm->p[i].iscow) kprintf(" cow");
     if (mm->p[i].readonlyfile) kprintf(" readonlyfile");
     if (mm->p[i].size !=