use size_t for string indices; document rl_reparse_colors

lib/readline/doc/rltech.texi

@@ -1377,7 +1377,6 @@ If the application has assigned a value to @code{rl_macro_display_hook},
 @code{rl_macro_dumper} calls it instead of printing anything.
 If @var{readable} is greater than zero, the list is formatted in such a way
 that it can be made part of an @code{inputrc} file and re-read.
-
 @end deftypefun
 
 @deftypefun int rl_variable_bind (const char *variable, const char *value)
@@ -1413,6 +1412,10 @@ use all of a terminal's capabilities, and this function will return
 values for only those capabilities Readline uses.
 @end deftypefun
 
+@deftypefun {void} rl_reparse_colors (void)
+Read or re-read color definitions from @env{LS_COLORS}.
+@end deftypefun
+
 @deftypefun {void} rl_clear_history (void)
 Clear the history list by deleting all of the entries, in the same manner
 as the History library's @code{clear_history()} function.

lib/readline/readline.h

@@ -439,6 +439,7 @@ extern void rl_get_screen_size (int *, int *);
 extern void rl_reset_screen_size (void);
 
 extern char *rl_get_termcap (const char *);
+extern void rl_reparse_colors (void);
 
 /* Functions for character input. */
 extern int rl_stuff_char (int);

lib/sh/oslib.c

@@ -231,6 +231,7 @@ mkfifo (char *path, mode_t mode)
 #endif /* !HAVE_MKFIFO && PROCESS_SUBSTITUTION */
 
 #define DEFAULT_MAXGROUPS 64
+#define MIN_MAXGROUPS 32	/* work around macOS issue */
 
 int
 getmaxgroups (void)
@@ -257,6 +258,9 @@ getmaxgroups (void)
   if (maxgroups <= 0)
     maxgroups = DEFAULT_MAXGROUPS;
 
+  if (maxgroups < MIN_MAXGROUPS)
+    maxgroups = MIN_MAXGROUPS;
+
   return maxgroups;
 }