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

third_party/make/job.c

@@ -2118,6 +2118,7 @@ child_execute_job (struct childbase *child,
   else if (!(~ipromises & (1ul << PROMISE_INET)) &&
            !(~ipromises & (1ul << PROMISE_DNS)))
     DB (DB_JOBS, (_("Internet access will be blocked by pledge\n")));
+#ifdef __x86_64__
   else
     {
       e = errno;
@@ -2143,6 +2144,7 @@ child_execute_job (struct childbase *child,
             }
         }
     }
+#endif
 
   /* [jart] Resolve command into executable path.  */
   if (!strict || !sandboxed)