libio: Do not autogenerate stdio_lim.h

Instead define the required fields in system dependend files.  The only
system dependent definition is FILENAME_MAX, which should match POSIX
PATH_MAX, and it is obtained from either kernel UAPI or mach headers.
Currently set pre-defined value from current kernels.

It avoids a circular dependendy when including stdio.h in
gen-as-const-headers files.

Checked on x86_64-linux-gnu and i686-linux-gnu
Reviewed-by: Carlos O'Donell <carlos@redhat.com>

libio/stdio.h

@@ -120,18 +120,23 @@ typedef __fpos64_t fpos64_t;
 # define P_tmpdir	"/tmp"
 #endif
 
+#define L_tmpnam 20
+#define TMP_MAX 238328
 
 /* Get the values:
-   L_tmpnam	How long an array of chars must be to be passed to `tmpnam'.
-   TMP_MAX	The minimum number of unique filenames generated by tmpnam
-		(and tempnam when it uses tmpnam's name space),
-		or tempnam (the two are separate).
-   L_ctermid	How long an array to pass to `ctermid'.
-   L_cuserid	How long an array to pass to `cuserid'.
-   FOPEN_MAX	Minimum number of files that can be open at once.
    FILENAME_MAX	Maximum length of a filename.  */
 #include <bits/stdio_lim.h>
 
+#ifdef __USE_POSIX
+# define L_ctermid 9
+# if !defined __USE_XOPEN2K || defined __USE_GNU
+#  define L_cuserid 9
+# endif
+#endif
+
+#undef  FOPEN_MAX
+#define FOPEN_MAX 16
+
 
 #if __GLIBC_USE (ISOC2X)
 /* Maximum length of printf output for a NaN.  */