tar: update ancient configure cruft

* configure.ac: Use AC_PROG_CC_STDC, not just AC_PROG_CC.
Remove obsolete macros AC_ISC_POSIX, AC_HEADER_SYS_WAIT,
AC_HEADER_DIRENT, AC_HEADER_STAT, AC_HEADER_STDC, AC_TYPE_SIGNAL,
AC_TYPE_SIZE_T.
* lib/prepargs.c (IN_CTYPE_DOMAIN): Remove.  All uses removed.
* src/list.c (from_header): Use isspace, not ISSPACE.
* src/system.c (pipe_handler, sys_exec_info_script):
* src/tar.c (sigstat):
Use void, not RETSIGTYPE.

configure.ac

@@ -27,14 +27,13 @@ AM_INIT_AUTOMAKE([1.11 gnits tar-ustar dist-bzip2 dist-xz dist-shar std-options
 # Enable silent rules by default:
 AM_SILENT_RULES([yes])
 
-AC_PROG_CC
+AC_PROG_CC_STDC
 AC_EXEEXT
 AC_PROG_RANLIB
 AC_PROG_YACC
 gl_EARLY
 
 AC_SYS_LARGEFILE
-AC_ISC_POSIX
 AC_C_INLINE
 
 AC_CHECK_HEADERS_ONCE(fcntl.h linux/fd.h memory.h net/errno.h \
@@ -49,12 +48,7 @@ AC_CHECK_HEADERS([sys/buf.h], [], [],
 #include <sys/param.h>
 #endif])
 
-AC_HEADER_SYS_WAIT
-
-AC_HEADER_DIRENT
 AC_HEADER_MAJOR
-AC_HEADER_STAT
-AC_HEADER_STDC
 
 AC_MSG_CHECKING([for st_fstype string in struct stat])
 AC_CACHE_VAL(diff_cv_st_fstype_string,
@@ -91,11 +85,9 @@ else
   export enable_acl=no
 fi
 
-AC_TYPE_SIGNAL
 AC_TYPE_MODE_T
 AC_TYPE_PID_T
 AC_TYPE_OFF_T
-AC_TYPE_SIZE_T
 AC_TYPE_UID_T
 AC_CHECK_TYPE(major_t, , AC_DEFINE(major_t, int,
 				   [Type of major device numbers.]))

lib/prepargs.c

@@ -29,16 +29,6 @@
 
 #include <ctype.h>
 
-/* IN_CTYPE_DOMAIN (C) is nonzero if the unsigned char C can safely be given
-   as an argument to <ctype.h> macros like "isspace".  */
-#ifdef STDC_HEADERS
-# define IN_CTYPE_DOMAIN(c) 1
-#else
-# define IN_CTYPE_DOMAIN(c) ((c) <= 0177)
-#endif
-
-#define ISSPACE(c) (IN_CTYPE_DOMAIN (c) && isspace (c))
-
 /* Find the white-space-separated options specified by OPTIONS, and
    using BUF to store copies of these options, set ARGV[0], ARGV[1],
    etc. to the option copies.  Return the number N of options found.
@@ -53,7 +43,7 @@ prepend_args (char const *options, char *buf, char **argv)
 
   for (;;)
     {
-      while (ISSPACE ((unsigned char) *o))
+      while (isspace ((unsigned char) *o))
 	o++;
       if (!*o)
 	return n;
@@ -64,7 +54,7 @@ prepend_args (char const *options, char *buf, char **argv)
       do
 	if ((*b++ = *o++) == '\\' && *o)
 	  b[-1] = *o++;
-      while (*o && ! ISSPACE ((unsigned char) *o));
+      while (*o && ! isspace ((unsigned char) *o));
 
       *b++ = '\0';
     }

src/list.c

@@ -723,7 +723,7 @@ from_header (char const *where0, size_t digs, char const *type,
 		    type));
 	  return -1;
 	}
-      if (!ISSPACE ((unsigned char) *where))
+      if (!isspace ((unsigned char) *where))
 	break;
       where++;
     }
@@ -861,7 +861,7 @@ from_header (char const *where0, size_t digs, char const *type,
 	value = -value;
     }
 
-  if (where != lim && *where && !ISSPACE ((unsigned char) *where))
+  if (where != lim && *where && !isspace ((unsigned char) *where))
     {
       if (type)
 	{

src/system.c

@@ -720,7 +720,7 @@ stat_to_env (char *name, char type, struct tar_stat_info *st)
 }
 
 static pid_t global_pid;
-static RETSIGTYPE (*pipe_handler) (int sig);
+static void (*pipe_handler) (int sig);
 
 int
 sys_exec_command (char *file_name, int typechar, struct tar_stat_info *st)
@@ -788,7 +788,7 @@ sys_exec_info_script (const char **archive_name, int volume_number)
   pid_t pid;
   char uintbuf[UINTMAX_STRSIZE_BOUND];
   int p[2];
-  static RETSIGTYPE (*saved_handler) (int sig);
+  static void (*saved_handler) (int sig);
 
   xpipe (p);
   saved_handler = signal (SIGPIPE, SIG_IGN);

src/tar.c

@@ -990,7 +990,7 @@ set_use_compress_program_option (const char *string)
   use_compress_program_option = string;
 }
 
-static RETSIGTYPE
+static void
 sigstat (int signo)
 {
   compute_duration ();