Make improvements

- Implement openpty()
- Add `--assimilate` flag to APE bootloader
- Restore Linux vDSO clock_gettime() support
- Use `$(APE_NO_MODIFY_SELF)` on more programs

libc/calls/asan.internal.h

@@ -0,0 +1,19 @@
+#ifndef COSMOPOLITAN_LIBC_CALLS_ASAN_INTERNAL_H_
+#define COSMOPOLITAN_LIBC_CALLS_ASAN_INTERNAL_H_
+#include "libc/bits/asmflag.h"
+#include "libc/calls/struct/timespec.h"
+#if !(__ASSEMBLER__ + __LINKER__ + 0)
+COSMOPOLITAN_C_START_
+
+forceinline bool __asan_is_valid_timespec(const struct timespec *ts) {
+  bool zf;
+  asm(ZFLAG_ASM("cmpw\t$0,0x7fff8000(%1)")
+      : ZFLAG_CONSTRAINT(zf)
+      : "r"((intptr_t)ts >> 3)
+      : "memory");
+  return zf;
+}
+
+COSMOPOLITAN_C_END_
+#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
+#endif /* COSMOPOLITAN_LIBC_CALLS_ASAN_INTERNAL_H_ */