Make some systemic improvements

- add vdso dump utility
- tests now log stack usage
- rename g_ftrace to __ftrace
- make internal spinlocks go faster
- add conformant c11 atomics library
- function tracing now logs stack usage
- make function call tracing thread safe
- add -X unsecure (no ssl) mode to redbean
- munmap() has more consistent behavior now
- pacify fsync() calls on python unit tests
- make --strace flag work better in redbean
- start minimizing and documenting compiler flags

libc/calls/readlinkat.c

@@ -16,12 +16,14 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/assert.h"
 #include "libc/bits/weaken.h"
 #include "libc/calls/internal.h"
 #include "libc/calls/strace.internal.h"
 #include "libc/dce.h"
 #include "libc/intrin/asan.internal.h"
 #include "libc/intrin/describeflags.internal.h"
+#include "libc/runtime/runtime.h"
 #include "libc/sysv/errfuns.h"
 #include "libc/zipos/zipos.internal.h"
 
@@ -50,6 +52,7 @@ ssize_t readlinkat(int dirfd, const char *path, char *buf, size_t bufsiz) {
              (bytes = __zipos_notat(dirfd, path)) == -1) {
     STRACE("TOOD: zipos support for readlinkat");
   } else if (!IsWindows()) {
+    assert(bufsiz);
     bytes = sys_readlinkat(dirfd, path, buf, bufsiz);
   } else {
     bytes = sys_readlinkat_nt(dirfd, path, buf, bufsiz);