Define _GLIBCXX_USE_DEV_RANDOM as replacement for _GLIBCXX_USE_RANDOM_TR1

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 6d68e907426..82a25e5f2f1 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -2073,27 +2073,31 @@  AC_DEFUN([GLIBCXX_CHECK_UCHAR_H], [
 
 
 dnl
-dnl Check whether "/dev/random" and "/dev/urandom" are available for the
+dnl Check whether "/dev/random" and "/dev/urandom" are available for
+dnl class std::random_device from C++ 2011 [rand.device], and
 dnl random_device of "TR1" (Chapter 5.1, "Random number generation").
 dnl
-AC_DEFUN([GLIBCXX_CHECK_RANDOM_TR1], [
+AC_DEFUN([GLIBCXX_CHECK_DEV_RANDOM], [
 
-  AC_MSG_CHECKING([for "/dev/random" and "/dev/urandom" for TR1 random_device])
-  AC_CACHE_VAL(glibcxx_cv_random_tr1, [
+  AC_MSG_CHECKING([for "/dev/random" and "/dev/urandom" for std::random_device])
+  AC_CACHE_VAL(glibcxx_cv_dev_random, [
     if test -r /dev/random && test -r /dev/urandom; then
-  ## For MSys environment the test above is detect as false-positive
-  ## on mingw-targets.  So disable it explicit for them.
+  ## For MSys environment the test above is detected as false-positive
+  ## on mingw-targets.  So disable it explicitly for them.
       case ${target_os} in
-	*mingw*) glibcxx_cv_random_tr1=no ;;
-	*) glibcxx_cv_random_tr1=yes ;;
+	*mingw*) glibcxx_cv_dev_random=no ;;
+	*) glibcxx_cv_dev_random=yes ;;
       esac
     else
-      glibcxx_cv_random_tr1=no;
+      glibcxx_cv_dev_random=no;
     fi
   ])
-  AC_MSG_RESULT($glibcxx_cv_random_tr1)
+  AC_MSG_RESULT($glibcxx_cv_dev_random)
 
-  if test x"$glibcxx_cv_random_tr1" = x"yes"; then
+  if test x"$glibcxx_cv_dev_random" = x"yes"; then
+    AC_DEFINE(_GLIBCXX_USE_DEV_RANDOM, 1,
+	      [Define if /dev/random and /dev/urandom are available for
+	       std::random_device.])
     AC_DEFINE(_GLIBCXX_USE_RANDOM_TR1, 1,
 	      [Define if /dev/random and /dev/urandom are available for
 	       the random_device of TR1 (Chapter 5.1).])
diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
index 332af3706d3..e3612b036df 100644
--- a/libstdc++-v3/configure.ac
+++ b/libstdc++-v3/configure.ac
@@ -255,8 +255,8 @@  if $GLIBCXX_IS_NATIVE; then
   GLIBCXX_CHECK_MATH_SUPPORT
   GLIBCXX_CHECK_STDLIB_SUPPORT
 
-  # For /dev/random and /dev/urandom for TR1.
-  GLIBCXX_CHECK_RANDOM_TR1
+  # For /dev/random and /dev/urandom for std::random_device.
+  GLIBCXX_CHECK_DEV_RANDOM
 
   # For TLS support.
   GCC_CHECK_TLS
diff --git a/libstdc++-v3/crossconfig.m4 b/libstdc++-v3/crossconfig.m4
index 0dbfe4057bd..3de40dc138b 100644
--- a/libstdc++-v3/crossconfig.m4
+++ b/libstdc++-v3/crossconfig.m4
@@ -66,6 +66,7 @@  case "${host}" in
     GLIBCXX_CHECK_LINKER_FEATURES
     GLIBCXX_CHECK_MATH_SUPPORT
     GLIBCXX_CHECK_STDLIB_SUPPORT
+    AC_DEFINE(_GLIBCXX_USE_DEV_RANDOM)
     AC_DEFINE(_GLIBCXX_USE_RANDOM_TR1)
     # We don't yet support AIX's TLS ABI.
     #GCC_CHECK_TLS
@@ -188,6 +189,7 @@  case "${host}" in
     GLIBCXX_CHECK_LINKER_FEATURES
     GLIBCXX_CHECK_MATH_SUPPORT
     GLIBCXX_CHECK_STDLIB_SUPPORT
+    AC_DEFINE(_GLIBCXX_USE_DEV_RANDOM)
     AC_DEFINE(_GLIBCXX_USE_RANDOM_TR1)
     GCC_CHECK_TLS
     AC_CHECK_FUNCS(__cxa_thread_atexit_impl)
diff --git a/libstdc++-v3/include/bits/random.h b/libstdc++-v3/include/bits/random.h
index e59c8b0221d..5e994aa8836 100644
--- a/libstdc++-v3/include/bits/random.h
+++ b/libstdc++-v3/include/bits/random.h
@@ -1602,7 +1602,7 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     // constructors, destructors and member functions
 
-#ifdef _GLIBCXX_USE_RANDOM_TR1
+#ifdef _GLIBCXX_USE_DEV_RANDOM
     random_device() { _M_init("default"); }
 
     explicit
@@ -1629,7 +1629,7 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     double
     entropy() const noexcept
     {
-#ifdef _GLIBCXX_USE_RANDOM_TR1
+#ifdef _GLIBCXX_USE_DEV_RANDOM
       return this->_M_getentropy();
 #else
       return 0.0;
@@ -1639,7 +1639,7 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     result_type
     operator()()
     {
-#ifdef _GLIBCXX_USE_RANDOM_TR1
+#ifdef _GLIBCXX_USE_DEV_RANDOM
       return this->_M_getval();
 #else
       return this->_M_getval_pretr1();
diff --git a/libstdc++-v3/testsuite/26_numerics/random/random_device/cons/token.cc b/libstdc++-v3/testsuite/26_numerics/random/random_device/cons/token.cc
index e2fc507fa5a..3d945ae12a1 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/random_device/cons/token.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/random_device/cons/token.cc
@@ -29,7 +29,7 @@ 
 void
 test01()
 {
-#ifdef _GLIBCXX_USE_RANDOM_TR1
+#ifdef _GLIBCXX_USE_DEV_RANDOM
   std::random_device x("/dev/random");
 #else
   std::random_device x("0");