Add cpu / mem / fsz limits to build system

Thanks to all the refactorings we now have the ability to enforce
reasonable limitations on the amount of resources any individual
compile or test can consume. Those limits are currently:

- `-C 8` seconds of 3.1ghz CPU time
- `-M 256mebibytes` of virtual memory
- `-F 100megabyte` limit on file size

Only one file currently needs to exceed these limits:

    o/$(MODE)/third_party/python/Objects/unicodeobject.o: \
        QUOTA += -C16  # overrides cpu limit to 16 seconds

This change introduces a new sizetol() function to LIBC_FMT for parsing
byte or bit size strings with Si unit suffixes. Functions like atoi()
have been rewritten too.

libc/log/oncrash.c

@@ -18,6 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/calls.h"
 #include "libc/calls/sigbits.h"
+#include "libc/calls/struct/sigaction.h"
 #include "libc/calls/struct/siginfo.h"
 #include "libc/calls/struct/utsname.h"
 #include "libc/calls/ucontext.h"
@@ -57,11 +58,21 @@ static const char kGregNames[17][4] forcealign(1) = {
 
 static const char kCpuFlags[12] forcealign(1) = "CVPRAKZSTIDO";
 static const char kFpuExceptions[6] forcealign(1) = "IDZOUP";
-static const char kCrashSigNames[8][5] forcealign(1) = {
-    "QUIT", "FPE", "ILL", "SEGV", "TRAP", "ABRT", "BUS", "PIPE"};
 
-hidden int kCrashSigs[8];
-hidden struct sigaction g_oldcrashacts[8];
+/* <SYNC-LIST>: showcrashreports.c, oncrashthunks.S, oncrash.c */
+int kCrashSigs[8];
+struct sigaction g_oldcrashacts[8];
+static const char kCrashSigNames[8][5] forcealign(1) = {
+    "QUIT",  //
+    "FPE",   //
+    "ILL",   //
+    "SEGV",  //
+    "TRAP",  //
+    "ABRT",  //
+    "BUS",   //
+    "PIPE",  //
+};
+/* </SYNC-LIST>: showcrashreports.c, oncrashthunks.S, oncrash.c */
 
 relegated static const char *TinyStrSignal(int sig) {
   size_t i;
@@ -76,7 +87,7 @@ relegated static const char *TinyStrSignal(int sig) {
 relegated static void ShowFunctionCalls(int fd, ucontext_t *ctx) {
   struct StackFrame *bp;
   struct StackFrame goodframe;
-  write(fd, "\r\n", 2);
+  write(fd, "\n", 1);
   if (ctx && ctx->uc_mcontext.rip && ctx->uc_mcontext.rbp) {
     goodframe.next = (struct StackFrame *)ctx->uc_mcontext.rbp;
     goodframe.addr = ctx->uc_mcontext.rip;
@@ -121,7 +132,7 @@ relegated static void DescribeCpuFlags(int fd, int flags, int x87sw,
 relegated static void ShowGeneralRegisters(int fd, ucontext_t *ctx) {
   size_t i, j, k;
   long double st;
-  write(fd, "\r\n", 2);
+  write(fd, "\n", 1);
   for (i = 0, j = 0, k = 0; i < ARRAYLEN(kGregNames); ++i) {
     if (j > 0) write(fd, " ", 1);
     dprintf(fd, "%-3s %016lx", kGregNames[(unsigned)kGregOrder[i]],
@@ -135,7 +146,7 @@ relegated static void ShowGeneralRegisters(int fd, ucontext_t *ctx) {
       }
       dprintf(fd, " %s(%zu) %Lg", "ST", k, st);
       ++k;
-      write(fd, "\r\n", 2);
+      write(fd, "\n", 1);
     }
   }
   DescribeCpuFlags(
@@ -147,9 +158,9 @@ relegated static void ShowGeneralRegisters(int fd, ucontext_t *ctx) {
 relegated static void ShowSseRegisters(int fd, ucontext_t *ctx) {
   size_t i;
   if (ctx->uc_mcontext.fpregs) {
-    write(fd, "\r\n\r\n", 4);
+    write(fd, "\n\n", 2);
     for (i = 0; i < 8; ++i) {
-      dprintf(fd, "%s%-2zu %016lx%016lx %s%-2d %016lx%016lx\r\n", "XMM", i + 0,
+      dprintf(fd, "%s%-2zu %016lx%016lx %s%-2d %016lx%016lx\n", "XMM", i + 0,
               ctx->uc_mcontext.fpregs->xmm[i + 0].u64[1],
               ctx->uc_mcontext.fpregs->xmm[i + 0].u64[0], "XMM", i + 8,
               ctx->uc_mcontext.fpregs->xmm[i + 8].u64[1],
@@ -174,32 +185,37 @@ relegated static void ShowMemoryMappings(int outfd) {
 }
 
 relegated static void ShowCrashReport(int err, int fd, int sig,
-                                      ucontext_t *ctx) {
+                                      struct siginfo *si, ucontext_t *ctx) {
   int i;
   char hostname[64];
   struct utsname names;
   strcpy(hostname, "unknown");
   gethostname(hostname, sizeof(hostname));
-  dprintf(fd, "\r\n%serror%s: Uncaught SIG%s on %s\r\n  %s\r\n  %s\r\n", RED2,
-          RESET, TinyStrSignal(sig), hostname, getauxval(AT_EXECFN),
-          strerror(err));
+  dprintf(fd,
+          "\n"
+          "%serror%s: Uncaught SIG%s (%s) on %s\n"
+          "  %s\n"
+          "  %s\n",
+          RED2, RESET, TinyStrSignal(sig),
+          si ? GetSiCodeName(sig, si->si_code) : "???", hostname,
+          getauxval(AT_EXECFN), strerror(err));
   if (uname(&names) != -1) {
-    dprintf(fd, "  %s %s %s %s\r\n", names.sysname, names.nodename,
-            names.release, names.version);
+    dprintf(fd, "  %s %s %s %s\n", names.sysname, names.nodename, names.release,
+            names.version);
   }
   ShowFunctionCalls(fd, ctx);
   if (ctx) {
     ShowGeneralRegisters(fd, ctx);
     ShowSseRegisters(fd, ctx);
   }
-  write(fd, "\r\n", 2);
+  write(fd, "\n", 1);
   ShowMemoryMappings(fd);
-  write(fd, "\r\n", 2);
+  write(fd, "\n", 1);
   for (i = 0; i < __argc; ++i) {
     write(fd, __argv[i], strlen(__argv[i]));
     write(fd, " ", 1);
   }
-  write(fd, "\r\n", 2);
+  write(fd, "\n", 1);
 }
 
 relegated static void RestoreDefaultCrashSignalHandlers(void) {
@@ -246,7 +262,7 @@ relegated void __oncrash(int sig, struct siginfo *si, ucontext_t *ctx) {
                            : 0);
   }
   if (gdbpid > 0 && (sig == SIGTRAP || sig == SIGQUIT)) return;
-  ShowCrashReport(err, STDERR_FILENO, sig, ctx);
+  ShowCrashReport(err, STDERR_FILENO, sig, si, ctx);
   exit(128 + sig);
   unreachable;
 }