--- /dev/null
+/* Generic alloca.h */
+
+#ifndef _AC_ALLOCA_H
+#define _AC_ALLOCA_H
+
+/* AIX requires this to be the first thing in the file. */
+#ifdef __GNUC__
+# define alloca __builtin_alloca
+#else
+# if HAVE_ALLOCA_H
+# include <alloca.h>
+# else
+# ifdef _AIX
+#pragma alloca
+# else
+# ifndef alloca /* predefined by HP cc +Olibcalls */
+char *alloca ();
+# endif
+# endif
+# endif
+#endif
+
+
+#endif /* _AC_ALLOCA_H */
--- /dev/null
+/* Generic dirent.h */
+
+#ifndef _AC_DIRENT_H
+#define _AC_DIRENT_H
+
+#if HAVE_DIRENT_H
+# include <dirent.h>
+# define NAMLEN(dirent) strlen((dirent)->d_name)
+#else
+# define dirent direct
+# define NAMLEN(dirent) (dirent)->d_namlen
+# if HAVE_SYS_NDIR_H
+# include <sys/ndir.h>
+# endif
+# if HAVE_SYS_DIR_H
+# include <sys/dir.h>
+# endif
+# if HAVE_NDIR_H
+# include <ndir.h>
+# endif
+#endif
+
+#endif /* _AC_DIRENT_H */
--- /dev/null
+/* Generic string.h */
+
+#ifndef _AC_STRING_H
+#define _AC_STRING_H
+
+#if STDC_HEADERS
+# include <string.h>
+#else
+# ifndef HAVE_STRCHR
+# define strchr index
+# define strrchr rindex
+# endif
+char *strchr (), *strrchr ();
+# ifndef HAVE_MEMCPY
+# define memcpy(d, s, n) bcopy ((s), (d), (n))
+# define memmove(d, s, n) bcopy ((s), (d), (n))
+# endif
+#endif
+
+#endif /* _AC_STRING_H */
--- /dev/null
+/* Generic time.h */
+
+#ifndef _AC_TIME_H
+#define _AC_TIME_H
+
+#if TIME_WITH_SYS_TIME
+# include <sys/time.h>
+# include <time.h>
+#else
+# if HAVE_SYS_TIME_H
+# include <sys/time.h>
+# else
+# include <time.h>
+# endif
+#endif
+
+#endif /* _AC_TIME_H */
--- /dev/null
+/* Generic unistd.h */
+
+#ifndef _AC_UNISTD_H
+#define _AC_UNISTD_H
+
+#if HAVE_UNISTD_H
+# include <sys/types.h>
+# include <unistd.h>
+#endif
+
+/* use _POSIX_VERSION for POSIX.1 code */
+
+#endif /* _AC_UNISTD_H */
--- /dev/null
+/* Generic wait.h */
+
+#ifndef _AC_WAIT_H
+#define _AC_WAIT_H
+
+#include <sys/types.h>
+#if HAVE_SYS_WAIT_H
+# include <sys/wait.h>
+#endif
+#ifndef WEXITSTATUS
+# define WEXITSTATUS(stat_val) ((unsigned)(stat_val) >> 8)
+#endif
+#ifndef WIFEXITED
+# define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
+#endif
+
+#endif /* _AC_WAIT_H */