Document __STDCPP_WANT_MATH_SPEC_FUNCS__ macro

	* doc/xml/manual/using.xml: Document __STDCPP_WANT_MATH_SPEC_FUNCS__.
	* doc/html/*: Regenerate.

From-SVN: r233645

libstdc++-v3/ChangeLog

 2016-02-23  Jonathan Wakely  <jwakely@redhat.com>
 
+	* doc/xml/manual/using.xml: Document __STDCPP_WANT_MATH_SPEC_FUNCS__.
+	* doc/html/*: Regenerate.
+
 	PR libstdc++/69893
 	* include/tr1/cmath (acosh, asinh, atanh, cbrt, copysign, erf, erfc,
 	exp2, expm1, fdim, fma, fmax, fmin, hypot, ilogb, lgamma, llrint,

libstdc++-v3/doc/html/manual/using_macros.html

@@ -89,4 +89,6 @@
       </p></dd><dt><span class="term"><code class="code">_GLIBCXX_PROFILE</code></span></dt><dd><p>Undefined by default. When defined, compiles user code
 	using the <a class="link" href="profile_mode.html" title="Chapter 19. Profile Mode">profile
 	mode</a>.
+      </p></dd><dt><span class="term"><code class="code">__STDCPP_WANT_MATH_SPEC_FUNCS__</code></span></dt><dd><p>Undefined by default. When defined to a non-zero integer constant,
+	enables support for ISO/IEC 29124 Special Math Functions.
       </p></dd></dl></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="using_headers.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="using.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="using_dual_abi.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Headers </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Dual ABI</td></tr></table></div></body></html>
\ No newline at end of file

libstdc++-v3/doc/xml/manual/using.xml

@@ -955,6 +955,13 @@ g++ -Winvalid-pch -I. -include stdc++.h -H -g -O2 hello.cc -o test.exe
 	mode</link>.
       </para>
     </listitem></varlistentry>
+
+    <varlistentry><term><code>__STDCPP_WANT_MATH_SPEC_FUNCS__</code></term>
+    <listitem>
+      <para>Undefined by default. When defined to a non-zero integer constant,
+	enables support for ISO/IEC 29124 Special Math Functions.
+      </para>
+    </listitem></varlistentry>
     </variablelist>
 
   </section>