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

tool/net/redbean.c

@@ -1091,7 +1091,6 @@ static void UpdateLuaPath(const char *s) {
 #endif
 }
 
-
 static void ProgramDirectory(const char *path) {
   char *s;
   size_t n;
@@ -5163,6 +5162,7 @@ static const luaL_Reg kLuaFuncs[] = {
     {"GetHeader", LuaGetHeader},                                //
     {"GetHeaders", LuaGetHeaders},                              //
     {"GetHost", LuaGetHost},                                    //
+    {"GetHostIsa", LuaGetHostIsa},                              //
     {"GetHostOs", LuaGetHostOs},                                //
     {"GetHttpReason", LuaGetHttpReason},                        //
     {"GetHttpVersion", LuaGetHttpVersion},                      //
@@ -6905,6 +6905,7 @@ static int HandleConnection(size_t i) {
 }
 
 static void MakeExecutableModifiable(void) {
+#ifdef __x86_64__
   int ft;
   size_t n;
   extern char ape_rom_vaddr[] __attribute__((__weak__));
@@ -6923,6 +6924,9 @@ static void MakeExecutableModifiable(void) {
     ftrace_install();
     ftrace_enabled(ft);
   }
+#else
+  // TODO
+#endif
 }
 
 static int HandleReadline(void) {