Refactor int/float128: NVCC -std=c++11

refactor the previous solution: nvcc with c++11 supports
__int128 and __float128

include/boost/config/compiler/gcc.hpp

@@ -133,14 +133,23 @@
 //
 // Recent GCC versions have __int128 when in 64-bit mode.
 //
-// We disable this if the compiler is really nvcc as it
+// We disable this if the compiler is really nvcc with C++03 as it
 // doesn't actually support __int128 as of CUDA_VERSION=7500
 // even though it defines __SIZEOF_INT128__.
 // See https://svn.boost.org/trac/boost/ticket/8048
+//     https://svn.boost.org/trac/boost/ticket/11852
 // Only re-enable this for nvcc if you're absolutely sure
 // of the circumstances under which it's supported:
 //
-#if defined(__SIZEOF_INT128__) && !defined(__CUDACC__)
+#if defined(__CUDACC__)
+#  if defined(BOOST_GCC_CXX11)
+#    define BOOST_NVCC_CXX11
+#  else
+#    define BOOST_NVCC_CXX03
+#  endif
+#endif
+
+#if defined(__SIZEOF_INT128__) && !defined(BOOST_NVCC_CXX03)
 #  define BOOST_HAS_INT128
 #endif
 //
@@ -149,7 +158,7 @@
 // be including <cstddef> later anyway when we select the std lib.
 //
 // Nevertheless, as of CUDA 7.5, using __float128 with the host
-// compiler is still not supported.
+// compiler in pre-C++11 mode is still not supported.
 // See https://svn.boost.org/trac/boost/ticket/11852
 //
 #ifdef __cplusplus
@@ -157,7 +166,7 @@
 #else
 #include <stddef.h>
 #endif
-#if defined(_GLIBCXX_USE_FLOAT128) && !defined(__STRICT_ANSI__) && !defined(__CUDACC__)
+#if defined(_GLIBCXX_USE_FLOAT128) && !defined(__STRICT_ANSI__) && !defined(BOOST_NVCC_CXX03)
 # define BOOST_HAS_FLOAT128
 #endif