Fix glibc presence checks that are incorrectly triggered in some cases.

src/platform-linux.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 28 matching lines @@
 #include <stdlib.h>
 
 // Ubuntu Dapper requires memory pages to be marked as
 // executable. Otherwise, OS raises an exception when executing code
 // in that page.
 #include <sys/types.h>  // mmap & munmap
 #include <sys/mman.h>   // mmap & munmap
 #include <sys/stat.h>   // open
 #include <fcntl.h>      // open
 #include <unistd.h>     // sysconf
-#ifdef __GLIBC__
+#if defined(__GLIBC__) && !defined(__UCLIBC__)
 #include <execinfo.h>   // backtrace, backtrace_symbols
-#endif  // def __GLIBC__
+#endif  // defined(__GLIBC__) && !defined(__UCLIBC__)
 #include <strings.h>    // index
 #include <errno.h>
 #include <stdarg.h>
 
 #undef MAP_TYPE
 
 #include "v8.h"
 
 #include "platform-posix.h"
 #include "platform.h"
@@ skipping 495 matching lines @@
                     fileno(f),
                     0);
   ASSERT(addr != MAP_FAILED);
   OS::Free(addr, size);
   fclose(f);
 }
 
 
 int OS::StackWalk(Vector<OS::StackFrame> frames) {
   // backtrace is a glibc extension.
-#ifdef __GLIBC__
+#if defined(__GLIBC__) && !defined(__UCLIBC__)
   int frames_size = frames.length();
   ScopedVector<void*> addresses(frames_size);
 
   int frames_count = backtrace(addresses.start(), frames_size);
 
   char** symbols = backtrace_symbols(addresses.start(), frames_count);
   if (symbols == NULL) {
     return kStackWalkError;
   }
 
   for (int i = 0; i < frames_count; i++) {
     frames[i].address = addresses[i];
     // Format a text representation of the frame based on the information
     // available.
     SNPrintF(MutableCStrVector(frames[i].text, kStackWalkMaxTextLen),
              "%s",
              symbols[i]);
     // Make sure line termination is in place.
     frames[i].text[kStackWalkMaxTextLen - 1] = '\0';
   }
 
   free(symbols);
 
   return frames_count;
-#else  // ndef __GLIBC__
+#else  // defined(__GLIBC__) && !defined(__UCLIBC__)
   return 0;
-#endif  // ndef __GLIBC__
+#endif  // defined(__GLIBC__) && !defined(__UCLIBC__)
 }
 
 
 // Constants used for mmap.
 static const int kMmapFd = -1;
 static const int kMmapFdOffset = 0;
 
 VirtualMemory::VirtualMemory() : address_(NULL), size_(0) { }
 
 VirtualMemory::VirtualMemory(size_t size) {
@@ skipping 652 matching lines @@
 
 
 void Sampler::Stop() {
   ASSERT(IsActive());
   SignalSender::RemoveActiveSampler(this);
   SetActive(false);
 }
 
 
 } }  // namespace v8::internal