Fix warnings

This change fixes Cosmopolitan so it has fewer opinions about compiler
warnings. The whole repository had to be cleaned up to be buildable in
-Werror -Wall mode. This lets us benefit from things like strict const
checking. Some actual bugs might have been caught too.

libc/log/backtrace2.c

@@ -49,12 +49,15 @@ static int PrintBacktraceUsingAddr2line(int fd, const struct StackFrame *bp) {
   ssize_t got;
   intptr_t addr;
   size_t i, j, gi;
+  char *p1, *p2, *p3;
   int ws, pid, pipefds[2];
   struct Garbages *garbage;
   const struct StackFrame *frame;
-  char *debugbin, *p1, *p2, *p3, *addr2line;
+  const char *debugbin, *addr2line;
   char buf[kBacktraceBufSize], *argv[kBacktraceMaxFrames];
 
+  (void)gi;
+
   // DWARF is a weak standard. Platforms that use LLVM or old GNU
   // usually can't be counted upon to print backtraces correctly.
   if (!IsLinux() && !IsWindows()) {
@@ -95,7 +98,7 @@ static int PrintBacktraceUsingAddr2line(int fd, const struct StackFrame *bp) {
   argv[i++] = "addr2line";
   argv[i++] = "-a"; /* filter out w/ shell script wrapper for old versions */
   argv[i++] = "-pCife";
-  argv[i++] = debugbin;
+  argv[i++] = (char *)debugbin;
   garbage = __tls_enabled ? __get_tls()->tib_garbages : 0;
   gi = garbage ? garbage->i : 0;
   for (frame = bp; frame && i < kBacktraceMaxFrames - 1; frame = frame->next) {