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/runtime/munmap.c

@@ -37,7 +37,6 @@
 
 #define IP(X)      (intptr_t)(X)
 #define ALIGNED(p) (!(IP(p) & (FRAMESIZE - 1)))
-#define ADDR(x)    ((int64_t)((uint64_t)(x) << 32) >> 16)
 #define FRAME(x)   ((int)((intptr_t)(x) >> 16))
 
 static noasan void MunmapShadow(char *p, size_t n) {
@@ -97,9 +96,9 @@ static noasan void MunmapImpl(char *p, size_t n) {
     }
     // openbsd even requires that if we mapped, for instance a 5 byte
     // file, that we be sure to call munmap(file, 5). let's abstract!
-    a = ADDR(beg);
-    b = ADDR(end) + FRAMESIZE;
-    c = ADDR(_mmi.p[i].x) + _mmi.p[i].size;
+    a = ADDR_32_TO_48(beg);
+    b = ADDR_32_TO_48(end) + FRAMESIZE;
+    c = ADDR_32_TO_48(_mmi.p[i].x) + _mmi.p[i].size;
     q = (char *)a;
     m = MIN(b, c) - a;
     if (!IsWindows()) {
@@ -119,23 +118,23 @@ noasan int _Munmap(char *p, size_t n) {
   intptr_t a, b, x, y;
   _unassert(!__vforked);
   if (UNLIKELY(!n)) {
-    STRACE("n=0");
+    STRACE("munmap n is 0");
     return einval();
   }
   if (UNLIKELY(!IsLegalSize(n))) {
-    STRACE("n isn't 48-bit");
+    STRACE("munmap n isn't 48-bit");
     return einval();
   }
   if (UNLIKELY(!IsLegalPointer(p))) {
-    STRACE("p isn't 48-bit");
+    STRACE("munmap p isn't 48-bit");
     return einval();
   }
   if (UNLIKELY(!IsLegalPointer(p + (n - 1)))) {
-    STRACE("p+(n-1) isn't 48-bit");
+    STRACE("munmap p+(n-1) isn't 48-bit");
     return einval();
   }
   if (UNLIKELY(!ALIGNED(p))) {
-    STRACE("p isn't 64kb aligned");
+    STRACE("munmap(%p) isn't 64kb aligned", p);
     return einval();
   }
   MunmapImpl(p, n);