Added <cmath> support to the TR1 library.

Added Borland and Sun workaround headers to the TR1 lib.
Added a "no tr1" version of cmath to Boost.Config and made use of it throughout Boost.Math.

[SVN r48054]

include/boost/config/no_tr1/cmath.hpp

@@ -0,0 +1,28 @@
+//  (C) Copyright John Maddock 2008.
+//  Use, modification and distribution are subject to the
+//  Boost Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// The aim of this header is just to include <cmath> but to do
+// so in a way that does not result in recursive inclusion of
+// the Boost TR1 components if boost/tr1/tr1/cmath is in the
+// include search path.  We have to do this to avoid circular
+// dependencies:
+//
+
+#ifndef BOOST_CONFIG_CMATH
+#  define BOOST_CONFIG_CMATH
+
+#  ifndef BOOST_TR1_NO_RECURSION
+#     define BOOST_TR1_NO_RECURSION
+#     define BOOST_CONFIG_NO_CMATH_RECURSION
+#  endif
+
+#  include <cmath>
+
+#  ifdef BOOST_CONFIG_NO_CMATH_RECURSION
+#     undef BOOST_TR1_NO_RECURSION
+#     undef BOOST_CONFIG_NO_CMATH_RECURSION
+#  endif
+
+#endif