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

include/cstd.h

@@ -27,9 +27,9 @@
  * <stddef.h>            Common macro definitions
  * <stdint.h> (C99)      Fixed-width integer types
  * <stdio.h>             Input/output program utilities
- *
- * General utilities:    memory management, program utilities, string
- *                       conversions, random numbers, algorithms
+ * <stdlib.h>            General utilities: memory management,
+ *                       program utilities, string conversions,
+ *                       random numbers, algorithms
  * <string.h>            String handling
  * <tgmath.h> (C99)      Type-generic math (macros wrapping math.h and
  *                       complex.h)
@@ -51,13 +51,17 @@
  *
  */
 #if !defined(__cplusplus)
-
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <signal.h>
 #include <assert.h>
 #include <stdarg.h>
 #include <ctype.h>
+#include <time.h>
 
+#else /* !__cplusplus */
+/* for FILE */
+#include <stdio.h>
 #endif /* !__cplusplus */
 #endif /* CSTD_H */

include/global.h

@@ -6,8 +6,6 @@
 #ifndef GLOBAL_H
 #define GLOBAL_H
 
-#include <stdio.h>
-
 /*
  * Files expected to exist in the playground directory (possibly inside
  * a dlb container file).

include/pcconf.h

@@ -111,33 +111,21 @@
 
 #if defined(_MSC_VER) && (_MSC_VER >= 7)
 #include <sys/types.h>
-#include <stdlib.h>
 #ifdef strcmpi
 #undef strcmpi
 #endif
-#include <string.h> /* Provides prototypes of strncmpi(), etc.     */
 #include <conio.h>
 #include <io.h>
 #include <direct.h>
 #define SIG_RET_TYPE void(__cdecl *)(int)
-#define M(c) ((char) (0x80 | (c)))
 #define vprintf printf
 #define vfprintf fprintf
 #define vsprintf sprintf
 #endif
 
-#if defined(__BORLANDC__) && defined(STRNCMPI)
-#include <string.h> /* Provides prototypes of strncmpi(), etc.     */
-#endif
-
-#if defined(__DJGPP__)
-#define _NAIVE_DOS_REGS
-#include <stdlib.h>
-#include <string.h> /* Provides prototypes of strncmpi(), etc.     */
 #ifndef M
 #define M(c) ((char) (0x80 | (c)))
 #endif
-#endif
 
 /*
  * On the VMS and unix, this option controls whether a delay is done by
@@ -226,10 +214,6 @@
 #define HLOCK "NHPERM"
 #endif
 
-#ifndef AMIGA
-#include <time.h>
-#endif
-
 /* the high quality random number routines */
 #ifndef USE_ISAAC64
 # ifdef RANDOM

include/unixconf.h

@@ -302,8 +302,6 @@
 
 #if defined(BSD) || defined(ULTRIX)
 #include <sys/time.h>
-#else
-#include <time.h>
 #endif
 
 /* these might be needed for include/system.h;
@@ -324,10 +322,7 @@
 #define SHELL /* do not delete the '!' command */
 #endif
 
-/* #include "system.h" */
-
 #if defined(POSIX_TYPES) || defined(__GNUC__)
-#include <stdlib.h>
 #include <unistd.h>
 #endif
 

include/vmsconf.h

@@ -213,7 +213,6 @@ PANICTRACE_GDB=2  #at conclusion of panic, show a call traceback and then
 #include <types.h>
 #include <unistd.h>
 #include <fcntl.h>
-#include <stdlib.h>
 #include <signal.h>
 #include <stat.h>
 #include <errno.h>
@@ -246,8 +245,6 @@ typedef int32_t off_t;
 #endif
 #endif /* _DECC_V4_SOURCE */
 
-#include <time.h>
-
 #ifndef VMSVSI
 #if 0 /* <file.h> is missing for old gcc versions; skip it to save time */
 #include <file.h>

include/windconf.h

@@ -165,8 +165,6 @@ typedef SSIZE_T ssize_t;
 
 
 #include <sys/types.h>
-#include <stdlib.h>
-#include <stdio.h>
 #ifdef __BORLANDC__
 #undef randomize
 #undef random
@@ -185,10 +183,6 @@ typedef SSIZE_T ssize_t;
 #endif
 
 #define NO_SIGNAL
-
-/* Time stuff */
-#include <time.h>
-
 #define USE_STDARG
 
 /* Use the high quality random number routines. */