build: fix build for SmartOS

This change in V8: https://code.google.com/p/v8/source/detail?r=22210
has introduced a method named OS::GetCurrentThreadId which fails to
compile on OSes where a "gettid" syscall does not exist.
This build issue has been fixed upstream by another change:
https://code.google.com/p/v8/source/detail?r=23459. This commit
integrates this fix. It's still not clear if this is good enough for the
long term, see https://code.google.com/p/v8/issues/detail?id=3620 for
more information.

The other build issue was due to the fact that alloca.h is not included
by other system includes on SmartOS, which is assumed by V8.

PR-URL: https://github.com/joyent/node/pull/8534
Reviewed-By: Fedor Indutny <fedor@indutny.com>

deps/v8/src/base/platform/platform-posix.cc

@@ -323,8 +323,12 @@ int OS::GetCurrentProcessId() {
 int OS::GetCurrentThreadId() {
 #if defined(ANDROID)
   return static_cast<int>(syscall(__NR_gettid));
-#else
+#elif defined(SYS_gettid)
   return static_cast<int>(syscall(SYS_gettid));
+#else
+  // PNaCL doesn't have a way to get an integral thread ID, but it doesn't
+  // really matter, because we only need it in PerfJitLogger::LogRecordedBuffer.
+  return 0;
 #endif  // defined(ANDROID)
 }
 

deps/v8/src/base/platform/platform.h

@@ -35,6 +35,7 @@ namespace std {
 int signbit(double x);
 }
 # endif
+#include <alloca.h>
 #endif
 
 #if V8_OS_QNX