Make improvements

This change progresses our AARCH64 support:

- The AARCH64 build and tests are now passing
- Add 128-bit floating-point support to printf()
- Fix clone() so it initializes cosmo's x28 TLS register
- Fix TLS memory layout issue with aarch64 _Alignas vars
- Revamp microbenchmarking tools so they work on aarch64
- Make some subtle improvements to aarch64 crash reporting
- Make kisdangerous() memory checks more accurate on aarch64
- Remove sys_open() since it's not available on Linux AARCH64

This change makes general improvements to Cosmo and Redbean:

- Introduce GetHostIsa() function in Redbean
- You can now feature check using pledge(0, 0)
- You can now feature check using unveil("",0)
- Refactor some more x86-specific asm comments
- Refactor and write docs for some libm functions
- Make the mmap() API behave more similar to Linux
- Fix WIFSIGNALED() which wrongly returned true for zero
- Rename some obscure cosmo keywords from noFOO to dontFOO

libc/intrin/printmemoryintervals.c

@@ -23,8 +23,6 @@
 #include "libc/macros.internal.h"
 #include "libc/runtime/memtrack.internal.h"
 
-#define ADDR(x) ((intptr_t)((int64_t)((uint64_t)(x) << 32) >> 16))
-
 static bool IsNoteworthyHole(unsigned i, const struct MemoryIntervals *mm) {
   // gaps between shadow frames aren't interesting
   // the chasm from heap to stack ruins statistics