AIX: Disable backtrace API call

Backtrace() and backtrace_symbols() API are not supported on
AIX and there are no user-mode equivalent API for the same.
For now, disabling the call to those API.
Currently this is preventing V8 to build on AIX.
This debug functionality was added in
https://codereview.chromium.org/2248393002

R=rmcilroy@chromium.org

BUG=
LOG=N

Review-Url: https://codereview.chromium.org/2324453002
Cr-Commit-Position: refs/heads/master@{#39356}

src/base/debug/stack_trace_posix.cc

@@ -135,6 +135,7 @@ void OutputPointer(void* pointer, BacktraceOutputHandler* handler) {
   handler->HandleOutput(buf);
 }
 
+#if !V8_OS_AIX
 void ProcessBacktrace(void* const* trace, size_t size,
                       BacktraceOutputHandler* handler) {
   // NOTE: This code MUST be async-signal safe (it's used by in-process
@@ -171,6 +172,7 @@ void ProcessBacktrace(void* const* trace, size_t size,
     }
   }
 }
+#endif  // !V8_OS_AIX
 
 void PrintToStderr(const char* output) {
   // NOTE: This code MUST be async-signal safe (it's used by in-process
@@ -359,23 +361,31 @@ StackTrace::StackTrace() {
   // NOTE: This code MUST be async-signal safe (it's used by in-process
   // stack dumping signal handler). NO malloc or stdio is allowed here.
 
+#if !V8_OS_AIX
   // Though the backtrace API man page does not list any possible negative
   // return values, we take no chance.
   count_ = static_cast<size_t>(backtrace(trace_, arraysize(trace_)));
+#else
+  count_ = 0;
+#endif
 }
 
 void StackTrace::Print() const {
   // NOTE: This code MUST be async-signal safe (it's used by in-process
   // stack dumping signal handler). NO malloc or stdio is allowed here.
 
+#if !V8_OS_AIX
   PrintBacktraceOutputHandler handler;
   ProcessBacktrace(trace_, count_, &handler);
+#endif
 }
 
+#if !V8_OS_AIX
 void StackTrace::OutputToStream(std::ostream* os) const {
   StreamBacktraceOutputHandler handler(os);
   ProcessBacktrace(trace_, count_, &handler);
 }
+#endif
 
 namespace internal {
 

src/v8.gyp

@@ -1979,6 +1979,7 @@
         ],
         ['OS=="aix"', {
           'sources': [
+            'base/debug/stack_trace_posix.cc',
             'base/platform/platform-aix.cc',
             'base/platform/platform-posix.cc'
           ]},