Fix bugs in cosmocc toolchain

This change integrates e58abc1110b335a3341e8ad5821ad8e3880d9bb2 from
https://github.com/ahgamut/musl-cross-make/ which fixes the issues we
were having with our C language extension for symbolic constants. This
change also performs some code cleanup and bug fixes to getaddrinfo().
It's now possible to compile projects like ncurses, readline and python
without needing to patch anything upstream, except maybe a line or two.
Pretty soon it should be possible to build a Linux distro on Cosmo.

tool/net/lfuncs.c

@@ -298,7 +298,7 @@ int LuaParseParams(lua_State *L) {
       return 1;
     } else {
       luaL_error(L, "out of memory");
-      unreachable;
+      __builtin_unreachable();
     }
   } else {
     return lua_gettop(L);
@@ -321,7 +321,7 @@ int LuaParseHost(lua_State *L) {
       return 1;
     } else {
       luaL_error(L, "out of memory");
-      unreachable;
+      __builtin_unreachable();
     }
   } else {
     return lua_gettop(L);
@@ -340,7 +340,7 @@ int LuaBsr(lua_State *L) {
     return 1;
   } else {
     luaL_argerror(L, 1, "zero");
-    unreachable;
+    __builtin_unreachable();
   }
 }
 
@@ -351,7 +351,7 @@ int LuaBsf(lua_State *L) {
     return 1;
   } else {
     luaL_argerror(L, 1, "zero");
-    unreachable;
+    __builtin_unreachable();
   }
 }
 
@@ -381,7 +381,7 @@ int LuaIndentLines(lua_State *L) {
     j = luaL_optinteger(L, 2, 1);
     if (!(0 <= j && j <= 65535)) {
       luaL_argerror(L, 2, "not in range 0..65535");
-      unreachable;
+      __builtin_unreachable();
     }
     p = IndentLines(p, n, &n, j);
     lua_pushlstring(L, p, n);
@@ -400,7 +400,7 @@ int LuaGetMonospaceWidth(lua_State *L) {
     w = strwidth(luaL_checkstring(L, 1), luaL_optinteger(L, 2, 0) & 7);
   } else {
     luaL_argerror(L, 1, "not integer or string");
-    unreachable;
+    __builtin_unreachable();
   }
   lua_pushinteger(L, w);
   return 1;
@@ -490,7 +490,7 @@ int LuaBarf(lua_State *L) {
     offset = luaL_checkinteger(L, 5);
     if (offset < 1) {
       luaL_error(L, "offset must be >= 1");
-      unreachable;
+      __builtin_unreachable();
     }
     --offset;
   }
@@ -498,11 +498,11 @@ int LuaBarf(lua_State *L) {
   flags = O_WRONLY | O_SEQUENTIAL | luaL_optinteger(L, 4, O_TRUNC | O_CREAT);
   if (flags & O_NONBLOCK) {
     luaL_error(L, "O_NONBLOCK not allowed");
-    unreachable;
+    __builtin_unreachable();
   }
   if ((flags & O_APPEND) && offset) {
     luaL_error(L, "O_APPEND with offset not possible");
-    unreachable;
+    __builtin_unreachable();
   }
   if ((fd = open(luaL_checkstring(L, 1), flags, mode)) == -1) {
     return LuaUnixSysretErrno(L, "open", olderr);
@@ -555,7 +555,7 @@ static int LuaCheckControlFlags(lua_State *L, int idx) {
   int f = luaL_optinteger(L, idx, 0);
   if (f & ~(kControlWs | kControlC0 | kControlC1)) {
     luaL_argerror(L, idx, "invalid control flags");
-    unreachable;
+    __builtin_unreachable();
   }
   return f;
 }
@@ -582,7 +582,7 @@ int LuaEncodeLatin1(lua_State *L) {
     return 1;
   } else {
     luaL_error(L, "out of memory");
-    unreachable;
+    __builtin_unreachable();
   }
 }
 
@@ -592,7 +592,7 @@ int LuaGetRandomBytes(lua_State *L) {
   n = luaL_optinteger(L, 1, 16);
   if (!(n > 0 && n <= 256)) {
     luaL_argerror(L, 1, "not in range 1..256");
-    unreachable;
+    __builtin_unreachable();
   }
   CHECK_EQ(n, getrandom(luaL_buffinitsize(L, &buf, n), n, 0));
   luaL_pushresultsize(&buf, n);
@@ -664,7 +664,7 @@ static dontinline int LuaCoderImpl(lua_State *L,
       free(p);
     } else {
       luaL_error(L, "out of memory");
-      unreachable;
+      __builtin_unreachable();
     }
     return 1;
   } else {
@@ -739,7 +739,7 @@ int LuaEscapeLiteral(lua_State *L) {
     return 1;
   } else {
     luaL_error(L, "out of memory");
-    unreachable;
+    __builtin_unreachable();
   }
 }
 
@@ -856,7 +856,7 @@ int LuaBenchmark(lua_State *L) {
       break;
     } else if (attempts >= maxattempts) {
       luaL_error(L, "system is under too much load to run benchmark");
-      unreachable;
+      __builtin_unreachable();
     }
   }
   overhead = avgticks;
@@ -878,7 +878,7 @@ int LuaBenchmark(lua_State *L) {
       break;
     } else if (attempts >= maxattempts) {
       luaL_error(L, "system is under too much load to run benchmark");
-      unreachable;
+      __builtin_unreachable();
     }
   }
   avgticks = MAX(avgticks - overhead, 0);
@@ -898,12 +898,12 @@ static void LuaCompress2(lua_State *L, void *dest, size_t *destLen,
       break;
     case Z_BUF_ERROR:
       luaL_error(L, "out of memory");
-      unreachable;
+      __builtin_unreachable();
     case Z_STREAM_ERROR:
       luaL_error(L, "invalid level");
-      unreachable;
+      __builtin_unreachable();
     default:
-      unreachable;
+      __builtin_unreachable();
   }
 }
 
@@ -948,7 +948,7 @@ int LuaUncompress(lua_State *L) {
   if (lua_isnoneornil(L, 2)) {
     if ((rc = unuleb64(p, n, &m)) == -1 || n < rc + 4) {
       luaL_error(L, "compressed value too short to be valid");
-      unreachable;
+      __builtin_unreachable();
     }
     len = m;
     crc = READ32LE(p + rc);
@@ -956,14 +956,14 @@ int LuaUncompress(lua_State *L) {
     if (uncompress((void *)q, &m, (unsigned char *)p + rc + 4, n) != Z_OK ||
         m != len || crc32_z(0, q, m) != crc) {
       luaL_error(L, "compressed value is corrupted");
-      unreachable;
+      __builtin_unreachable();
     }
   } else {
     len = m = luaL_checkinteger(L, 2);
     q = luaL_buffinitsize(L, &buf, m);
     if (uncompress((void *)q, &m, (void *)p, n) != Z_OK || m != len) {
       luaL_error(L, "compressed value is corrupted");
-      unreachable;
+      __builtin_unreachable();
     }
   }
   luaL_pushresultsize(&buf, m);