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

test/libc/calls/pledge2_test.c

@@ -25,6 +25,7 @@
 #include "libc/intrin/promises.internal.h"
 #include "libc/runtime/runtime.h"
 #include "libc/sock/sock.h"
+#include "libc/stdio/stdio.h"
 #include "libc/sysv/consts/af.h"
 #include "libc/sysv/consts/ipproto.h"
 #include "libc/sysv/consts/sig.h"
@@ -32,10 +33,11 @@
 #include "libc/testlib/subprocess.h"
 #include "libc/testlib/testlib.h"
 
-#ifdef __x86_64__
-
 void SetUp(void) {
-  if (!__is_linux_2_6_23() && !IsOpenbsd()) exit(0);
+  if (pledge(0, 0) == -1) {
+    fprintf(stderr, "warning: pledge() not supported on this system\n");
+    exit(0);
+  }
 }
 
 TEST(pledge, testSoftError) {
@@ -116,5 +118,3 @@ TEST(pledge, testEmptyPledge_doesntUseTrapping) {
   socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
   TERMS(IsOpenbsd() ? SIGABRT : SIGSYS);
 }
-
-#endif /* __x86_64__ */