Remove excess whitespace from doc strings of some commands

I've noticed that doc strings of some commands, like "set cwd"
and  "set inferior-tty", have some excess whitespace, which
makes them display with unexpected indentation, at least in a
Windows command prompt window.  This patch fixes that.

* gdb/linux-nat.c (_initialize_linux_nat):
* gdb/riscv-tdep.c (riscv_insn):
* gdb/top.c (quit_force):
* gdb/infcmd.c (_initialize_infcmd): Remove excess whitespace.

gdb/infcmd.c

@@ -3093,10 +3093,10 @@ _initialize_infcmd ()
   /* Add the filename of the terminal connected to inferior I/O.  */
   auto tty_set_show
     = add_setshow_optional_filename_cmd ("inferior-tty", class_run, _("\
-Set terminal for future runs of program being debugged."), _("		\
-Show terminal for future runs of program being debugged."), _("		\
-Usage: set inferior-tty [TTY]\n\n					\
-If TTY is omitted, the default behavior of using the same terminal as GDB\n \
+Set terminal for future runs of program being debugged."), _("\
+Show terminal for future runs of program being debugged."), _("\
+Usage: set inferior-tty [TTY]\n\n\
+If TTY is omitted, the default behavior of using the same terminal as GDB\n\
 is restored."),
 					 set_tty_value,
 					 get_tty_value,
@@ -3117,8 +3117,8 @@ Follow this command with any number of args, to be passed to the program."),
 
   auto cwd_set_show
     = add_setshow_string_noescape_cmd ("cwd", class_run, _("\
-Set the current working directory to be used when the inferior is started.\n \
-Changing this setting does not have any effect on inferiors that are\n	\
+Set the current working directory to be used when the inferior is started.\n\
+Changing this setting does not have any effect on inferiors that are\n\
 already running."),
 				       _("\
 Show the current working directory that is used when the inferior is started."),

gdb/linux-nat.c

@@ -4701,8 +4701,8 @@ _initialize_linux_nat ()
 {
   add_setshow_boolean_cmd ("linux-nat", class_maintenance,
 			   &debug_linux_nat, _("\
-Set debugging of GNU/Linux native target."), _("	\
-Show debugging of GNU/Linux native target."), _("	\
+Set debugging of GNU/Linux native target."), _("\
+Show debugging of GNU/Linux native target."), _("\
 When on, print debug messages relating to the GNU/Linux native target."),
 			   nullptr,
 			   show_debug_linux_nat,

gdb/riscv-tdep.c

@@ -4821,7 +4821,7 @@ initialisation process."),
   add_setshow_auto_boolean_cmd ("use-compressed-breakpoints", no_class,
 				&use_compressed_breakpoints,
 				_("\
-Set debugger's use of compressed breakpoints."), _("	\
+Set debugger's use of compressed breakpoints."), _("\
 Show debugger's use of compressed breakpoints."), _("\
 Debugging compressed code requires compressed breakpoints to be used. If\n\
 left to 'auto' then gdb will use them if the existing instruction is a\n\

gdb/top.c

@@ -2267,7 +2267,7 @@ input settings."),
 
   add_setshow_boolean_cmd ("startup-quietly", class_support,
 			       &startup_quiet, _("\
-Set whether GDB should start up quietly."), _("		\
+Set whether GDB should start up quietly."), _("\
 Show whether GDB should start up quietly."), _("\
 This setting will not affect the current session.  Instead this command\n\
 should be added to the .gdbearlyinit file in the users home directory to\n\