Move mi_interpreter to mi-interp.h

I noticed that touching interps.h caused a lot of recompilation.  I
tracked this down to mi-common.h including this file.  This patch
moves the MI interpreter to mi-interp.h, which cuts down on
recompilation when modifying interps.h.

gdb/mi/mi-common.h

@@ -19,10 +19,6 @@
 #ifndef MI_MI_COMMON_H
 #define MI_MI_COMMON_H
 
-#include "interps.h"
-
-struct mi_console_file;
-
 /* Represents the reason why GDB is sending an asynchronous command to
    the front end.  NOTE: When modifing this, don't forget to update
    gdb.texinfo!  */
@@ -52,50 +48,4 @@ enum async_reply_reason
 
 const char *async_reason_lookup (enum async_reply_reason reason);
 
-/* An MI interpreter.  */
-
-class mi_interp final : public interp
-{
-public:
-  mi_interp (const char *name)
-    : interp (name)
-  {}
-
-  void init (bool top_level) override;
-  void resume () override;
-  void suspend () override;
-  gdb_exception exec (const char *command_str) override;
-  ui_out *interp_ui_out () override;
-  void set_logging (ui_file_up logfile, bool logging_redirect,
-		    bool debug_redirect) override;
-  void pre_command_loop () override;
-
-  /* MI's output channels */
-  mi_console_file *out;
-  mi_console_file *err;
-  mi_console_file *log;
-  mi_console_file *targ;
-  mi_console_file *event_channel;
-
-  /* Raw console output.  */
-  struct ui_file *raw_stdout;
-
-  /* Raw logfile output.  */
-  struct ui_file *raw_stdlog;
-
-  /* Save the original value of raw_stdout and raw_stdlog here when logging, and
-     the file which we need to delete, so we can restore correctly when
-     done.  */
-  struct ui_file *saved_raw_stdout;
-  struct ui_file *saved_raw_stdlog;
-  struct ui_file *saved_raw_file_to_delete;
-
-
-  /* MI's builder.  */
-  struct ui_out *mi_uiout;
-
-  /* MI's CLI builder (wraps OUT).  */
-  struct ui_out *cli_uiout;
-};
-
 #endif /* MI_MI_COMMON_H */

gdb/mi/mi-interp.h

@@ -20,6 +20,56 @@
 #ifndef MI_MI_INTERP_H
 #define MI_MI_INTERP_H
 
+#include "interps.h"
+
+struct mi_console_file;
+
+/* An MI interpreter.  */
+
+class mi_interp final : public interp
+{
+public:
+  mi_interp (const char *name)
+    : interp (name)
+  {}
+
+  void init (bool top_level) override;
+  void resume () override;
+  void suspend () override;
+  gdb_exception exec (const char *command_str) override;
+  ui_out *interp_ui_out () override;
+  void set_logging (ui_file_up logfile, bool logging_redirect,
+		    bool debug_redirect) override;
+  void pre_command_loop () override;
+
+  /* MI's output channels */
+  mi_console_file *out;
+  mi_console_file *err;
+  mi_console_file *log;
+  mi_console_file *targ;
+  mi_console_file *event_channel;
+
+  /* Raw console output.  */
+  struct ui_file *raw_stdout;
+
+  /* Raw logfile output.  */
+  struct ui_file *raw_stdlog;
+
+  /* Save the original value of raw_stdout and raw_stdlog here when logging, and
+     the file which we need to delete, so we can restore correctly when
+     done.  */
+  struct ui_file *saved_raw_stdout;
+  struct ui_file *saved_raw_stdlog;
+  struct ui_file *saved_raw_file_to_delete;
+
+
+  /* MI's builder.  */
+  struct ui_out *mi_uiout;
+
+  /* MI's CLI builder (wraps OUT).  */
+  struct ui_out *cli_uiout;
+};
+
 /* Output the shared object attributes to UIOUT.  */
 
 void mi_output_solib_attribs (ui_out *uiout, struct so_list *solib);

gdb/mi/mi-main.c

@@ -40,7 +40,7 @@
 #include "regcache.h"
 #include "frame.h"
 #include "mi-main.h"
-#include "mi-common.h"
+#include "mi-interp.h"
 #include "language.h"
 #include "valprint.h"
 #include "osdata.h"