Mention clog10{,f,l} in documentation (Builtins section)

	* doc/extend.texi: Mention clog10, clog10f an clog10l
	in Builtins section.

From-SVN: r233738

gcc/ChangeLog

 2016-02-26  Martin Liska  <mliska@suse.cz>
 
+	* doc/extend.texi: Mention clog10, clog10f an clog10l
+	in Builtins section.
+
+2016-02-26  Martin Liska  <mliska@suse.cz>
+
 	* dwarf2out.c (new_loc_descr): Replace ENABLE_CHECKING with
 	CHECKING_P.
 	(resolve_args_picking_1): Likewise.

gcc/doc/extend.texi

@@ -10217,6 +10217,9 @@ in the Cilk Plus language manual which can be found at
 @findex clog
 @findex clogf
 @findex clogl
+@findex clog10
+@findex clog10f
+@findex clog10l
 @findex conj
 @findex conjf
 @findex conjl
@@ -10633,6 +10636,10 @@ that are recognized in any mode since ISO C90 reserves these names for
 the purpose to which ISO C99 puts them.  All these functions have
 corresponding versions prefixed with @code{__builtin_}.
 
+There are also GNU extension functions @code{clog10}, @code{clog10f} and
+@code{clog10l} which names are reserved by ISO C99 for future use.
+All these functions have versions prefixed with @code{__builtin_}.
+
 The ISO C94 functions
 @code{iswalnum}, @code{iswalpha}, @code{iswcntrl}, @code{iswdigit},
 @code{iswgraph}, @code{iswlower}, @code{iswprint}, @code{iswpunct},