src: Only use TR1 type_traits on OSX<10.9

src: Only use TR1 type_traits on OSX<10.9 · nodejs/node@34d58ce

Original file line number	Diff line number	Diff line change
`@@ -11,7 +11,12 @@`
`11`	`11`	`#include <stdio.h>`
`12`	`12`	`#include <stdlib.h>`
`13`	`13`
`14`		`-#ifdef __APPLE__`
	`14`	`+// OSX 10.9 defaults to libc++ which provides a C++11 <type_traits> header.`
	`15`	`+#if defined(__APPLE__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 1090`
	`16`	`+#define USE_TR1_TYPE_TRAITS`
	`17`	`+#endif`
	`18`	`+`
	`19`	`+#ifdef USE_TR1_TYPE_TRAITS`
`15`	`20`	`#include <tr1/type_traits> // NOLINT(build/c++tr1)`
`16`	`21`	`#else`
`17`	`22`	`#include <type_traits> // std::remove_reference`
`@@ -31,7 +36,7 @@ NO_RETURN void Abort();`
`31`	`36`	`NO_RETURN void Assert(const char* const (*args)[4]);`
`32`	`37`	`void DumpBacktrace(FILE* fp);`
`33`	`38`
`34`		`-#ifdef __APPLE__`
	`39`	`+#ifdef USE_TR1_TYPE_TRAITS`
`35`	`40`	`template <typename T> using remove_reference = std::tr1::remove_reference<T>;`
`36`	`41`	`#else`
`37`	`42`	`template <typename T> using remove_reference = std::remove_reference<T>;`