Remove explanatory comments from includes

I noticed a comment by an include and remembered that I think these
don't really provide much value -- sometimes they are just editorial,
and sometimes they are obsolete.  I think it's better to just remove
them.  Tested by rebuilding.

Approved-By: Andrew Burgess <aburgess@redhat.com>

gdb/python/py-finishbreakpoint.c

@@ -20,7 +20,7 @@
 
 
 #include "defs.h"
-#include "top.h"		/* For quit_force().  */
+#include "top.h"
 #include "python-internal.h"
 #include "breakpoint.h"
 #include "frame.h"

gdb/python/py-symbol.c

@@ -18,7 +18,7 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include "defs.h"
-#include "top.h"		/* For force_quit ().  */
+#include "top.h"
 #include "block.h"
 #include "frame.h"
 #include "symtab.h"

gdb/python/py-utils.c

@@ -18,7 +18,7 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include "defs.h"
-#include "top.h"		/* For quit_force ().  */
+#include "top.h"
 #include "charset.h"
 #include "value.h"
 #include "python-internal.h"

gdb/python/py-value.c

@@ -18,7 +18,7 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include "defs.h"
-#include "top.h"		/* For quit_force ().  */
+#include "top.h"
 #include "charset.h"
 #include "value.h"
 #include "language.h"