more C standard progress

There was a transcription error in the comments in cstd.h for
the standard list of header files, where only the description
remained for <stdlib.h>, not the name of the file itself.

Remove several extraneous inclusions of the standard C99 headers.

Tested on the following afterwards:
Linux (using hints/linux.370) including tty, curses, qt6, and X11
macOS (using hints/macOS.370) including tty, curses, qt5, and X11
Windows MSYS2 using sys/windows/GNUmakefile
Windows Visual Studio using sys/windows/Makefile.nmake
msdos cross-compile on Ubuntu using djgpp cross-compiler

src/allmain.c

@@ -6,7 +6,6 @@
 /* various code that was replicated in *main.c */
 
 #include "hack.h"
-#include <ctype.h>
 
 #ifndef NO_SIGNAL
 #include <signal.h>

src/attrib.c

@@ -5,7 +5,6 @@
 /*  attribute modification routines. */
 
 #include "hack.h"
-#include <ctype.h>
 
 /* part of the output on gain or loss of attribute */
 static const char

src/coloratt.c

@@ -3,7 +3,6 @@
 /* NetHack may be freely redistributed.  See license for details. */
 
 #include "hack.h"
-#include <ctype.h>
 
 struct color_names {
     const char *name;

src/end.c

@@ -9,7 +9,6 @@
 #ifndef NO_SIGNAL
 #include <signal.h>
 #endif
-#include <ctype.h>
 #ifndef LONG_MAX
 #include <limits.h>
 #endif

src/files.c

@@ -7,7 +7,6 @@
 
 #include "hack.h"
 #include "dlb.h"
-#include <ctype.h>
 
 #ifdef TTY_GRAPHICS
 #include "wintty.h" /* more() */
@@ -45,7 +44,6 @@ const
 #if defined(UNIX) && defined(SELECTSAVED)
 #include <sys/types.h>
 #include <dirent.h>
-#include <stdlib.h>
 #endif
 
 #if defined(UNIX) || defined(VMS) || !defined(NO_SIGNAL)

src/makemon.c

@@ -5,8 +5,6 @@
 
 #include "hack.h"
 
-#include <ctype.h>
-
 /* this assumes that a human quest leader or nemesis is an archetype
    of the corresponding role; that isn't so for some roles (tourist
    for instance) but is for the priests and monks we use it for... */

src/mon.c

@@ -5,7 +5,6 @@
 
 #include "hack.h"
 #include "mfndpos.h"
-#include <ctype.h>
 
 staticfn void sanity_check_single_mon(struct monst *, boolean, const char *);
 staticfn struct obj *make_corpse(struct monst *, unsigned);

src/report.c

@@ -9,7 +9,6 @@
 # ifndef NO_SIGNAL
 #include <signal.h>
 # endif
-#include <ctype.h>
 # ifndef LONG_MAX
 #include <limits.h>
 # endif

src/utf8map.c

@@ -3,7 +3,6 @@
 /* NetHack may be freely redistributed.  See license for details. */
 
 #include "hack.h"
-#include <ctype.h>
 
 #ifdef ENHANCED_SYMBOLS