No CrashHandler for NACL bots.

tools/CrashHandler.cpp

 #include "CrashHandler.h"
 
 #include "SkTypes.h"
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <signal.h>
 
 #if defined(SK_BUILD_FOR_MAC)
 
@@ skipping 21 matching lines @@
         abi::__cxa_demangle(mangled, demangled, &len, &ok);
 
         fprintf(stderr, "%s (+0x%zx)\n", ok == 0 ? demangled : mangled, (size_t)offset);
     }
     fprintf(stderr, "\n");
 
     // Exit NOW.  Don't notify other threads, don't call anything registered with atexit().
     _Exit(sig);
 }
 
-#elif defined(SK_BUILD_FOR_UNIX)
+#elif defined(SK_BUILD_FOR_UNIX) && !defined(SK_BUILD_FOR_NACL)   // NACL doesn't have backtrace().
 
 // We'd use libunwind here too, but it's a pain to get installed for both 32 and 64 bit on bots.
 // Doesn't matter much: catchsegv is best anyway.
 #include <execinfo.h>
 
 static void handler(int sig) {
     static const int kMax = 64;
     void* stack[kMax];
     const int count = backtrace(stack, kMax);
 
     fprintf(stderr, "\nSignal %d:\n", sig);
     backtrace_symbols_fd(stack, count, 2/*stderr*/);
 
     // Exit NOW.  Don't notify other threads, don't call anything registered with atexit().
     _Exit(sig);
 }
 
 #endif
 
-#if defined(SK_BUILD_FOR_UNIX) || defined(SK_BUILD_FOR_MAC)
+#if defined(SK_BUILD_FOR_MAC) || (defined(SK_BUILD_FOR_UNIX) && !defined(SK_BUILD_FOR_NACL))
 
 void SetupCrashHandler() {
     static const int kSignals[] = {
         SIGABRT,
         SIGBUS,
         SIGFPE,
         SIGILL,
         SIGSEGV,
     };
 
     for (size_t i = 0; i < sizeof(kSignals) / sizeof(kSignals[0]); i++) {
         // Register our signal handler unless something's already done so (e.g. catchsegv).
         void (*prev)(int) = signal(kSignals[i], handler);
         if (prev != SIG_DFL) {
             signal(kSignals[i], prev);
         }
     }
 }
 
 // TODO: #elif defined(SK_BUILD_FOR_WIN) when I find a Windows machine to work from.
 
 #else
 
 void SetupCrashHandler() { }
 
 #endif