Make build hermetic without shell scripts

- Fix some minor issues in ar.com
- Have execve() look for `ape` command
- Rewrite NT paths using /c/ rather /??/c:/
- Replace broken GCC symlinks with .sym files
- Rewrite $PATH environment variables on startup
- Make $(APE_NO_MODIFY_SELF) the default bootloader
- Add all build command dependencies to build/bootstrap
- Get the repository mostly building from source on non-Linux

test/libc/log/backtrace.c

@@ -0,0 +1,132 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2022 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/fmt/conv.h"
+#include "libc/limits.h"
+#include "libc/log/log.h"
+#include "libc/runtime/symbols.internal.h"
+#include "libc/stdio/stdio.h"
+#include "libc/str/str.h"
+
+int StackOverflow(int f(), int n) {
+  if (n < INT_MAX) {
+    return f(f, n + 1) - 1;
+  } else {
+    return INT_MAX;
+  }
+}
+
+void FpuCrash(void) {
+  typedef char xmm_t __attribute__((__vector_size__(16)));
+  xmm_t v = {0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7,
+             0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf};
+  volatile int x = 0;
+  asm volatile("fldpi");
+  asm volatile("mov\t%0,%%r15" : /* no outputs */ : "g"(0x3133731337));
+  asm volatile("movaps\t%0,%%xmm15" : /* no outputs */ : "x"(v));
+  fputc(7 / x, stdout);
+}
+
+char bss[10];
+void BssOverrunCrash(int n) {
+  int i;
+  for (i = 0; i < n; ++i) {
+    bss[i] = i;
+  }
+}
+
+char data[10] = "abcdeabcde";
+void DataOverrunCrash(int n) {
+  int i;
+  for (i = 0; i < n; ++i) {
+    data[i] = i;
+  }
+}
+
+const char rodata[10] = "abcdeabcde";
+int RodataOverrunCrash(int i) {
+  return rodata[i];
+}
+
+char *StackOverrunCrash(int n) {
+  int i;
+  char stack[10];
+  bzero(stack, sizeof(stack));
+  for (i = 0; i < n; ++i) {
+    stack[i] = i;
+  }
+  return strdup(stack);
+}
+
+char *MemoryLeakCrash(void) {
+  char *p = strdup("doge");
+  CheckForMemoryLeaks();
+  return p;
+}
+
+int NpeCrash(char *p) {
+  asm("nop");  // xxx: due to backtrace addr-1 thing
+  return *p;
+}
+
+void (*pFpuCrash)(void) = FpuCrash;
+void (*pBssOverrunCrash)(int) = BssOverrunCrash;
+void (*pDataOverrunCrash)(int) = DataOverrunCrash;
+int (*pRodataOverrunCrash)(int) = RodataOverrunCrash;
+char *(*pStackOverrunCrash)(int) = StackOverrunCrash;
+char *(*pMemoryLeakCrash)(void) = MemoryLeakCrash;
+int (*pNpeCrash)(char *) = NpeCrash;
+int (*pStackOverflow)(int (*)(), int) = StackOverflow;
+
+int main(int argc, char *argv[]) {
+  ShowCrashReports();
+  if (argc > 1) {
+    switch (atoi(argv[1])) {
+      case 0:
+        break;
+      case 1:
+        pFpuCrash();
+        exit(0);
+      case 2:
+        pBssOverrunCrash(10 + 1);
+        exit(0);
+      case 3:
+        exit(pRodataOverrunCrash(10 + 1));
+      case 4:
+        pDataOverrunCrash(10 + 1);
+        exit(0);
+      case 5:
+        exit((intptr_t)pStackOverrunCrash(10 + 1));
+      case 6:
+        exit((intptr_t)pMemoryLeakCrash());
+      case 7:
+        exit(pNpeCrash(0));
+      case 8:
+        __cxa_finalize(0);
+        exit(pNpeCrash(0));
+      case 9:
+        exit(pStackOverflow(pStackOverflow, 0));
+      default:
+        fputs("error: unrecognized argument\n", stderr);
+        exit(1);
+    }
+  } else {
+    fputs("error: too few args\n", stderr);
+    exit(1);
+  }
+}