Add "language-option" to -list-features

Following the addition of the --language optiton to all GDB/MI
commands,  I realized that there was no easy way for front-ends
to figure out whether this features is available or not. So I added
a "language-option" entry to -list-features.

gdb/ChangeLog:

        * mi/mi-main.c (mi_cmd_list_features): Add "language-options"
        to -list-features output.

gdb/doc/ChangeLog:

        * gdb.texinfo (GDB/MI Miscellaneous Commands): Document the new
        "language-option" entry in the output of the "-list-features"
        command.

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2013-11-18  Joel Brobecker  <brobecker@adacore.com>
+
+	* mi/mi-main.c (mi_cmd_list_features): Add "language-options"
+	to -list-features output.
+
 2013-11-17  Joel Brobecker  <brobecker@adacore.com>
 
 	* dwarf2expr.h (struct dwarf_expr_context_funcs)

gdb/doc/ChangeLog

@@ -1,3 +1,9 @@
+2013-11-18  Joel Brobecker  <brobecker@adacore.com>
+
+	* gdb.texinfo (GDB/MI Miscellaneous Commands): Document the new
+	"language-option" entry in the output of the "-list-features"
+	command.
+
 2013-11-15  Tom Tromey  <tromey@redhat.com>
 
 	* gdb.texinfo (Variables): Note gdb rules for ambiguous cases.

gdb/doc/gdb.texinfo

@@ -35119,6 +35119,9 @@ Indicates support for the @code{-ada-task-info} command.
 Indicates support for the following commands, all of them related to Ada
 exceptions: @code{-info-ada-exceptions}, @code{-catch-assert} and
 @code{-catch-exception}.
+@item language-option
+Indicates that all @sc{gdb/mi} commands accept the @option{--language}
+option (@pxref{Context management}).
 @end table
 
 @subheading The @code{-list-target-features} Command

gdb/mi/mi-main.c

@@ -1816,6 +1816,7 @@ mi_cmd_list_features (char *command, char **argv, int argc)
       ui_out_field_string (uiout, NULL, "breakpoint-notifications");
       ui_out_field_string (uiout, NULL, "ada-task-info");
       ui_out_field_string (uiout, NULL, "ada-exceptions");
+      ui_out_field_string (uiout, NULL, "language-option");
       
 #if HAVE_PYTHON
       if (gdb_python_initialized)