Add alt code to 1986/hague - fgets()

The reason it is in alt code is because one of the forms of input (see
below) will, although print out correct output, segfault after
outputting the text. That is when one does something like:

    echo foo | ./hague.alt

Whether it might be worth making it the entry itself with a note in the
Makefile and README.md and bugs.md (because it does print out correct
output) can be determined later - or not.

This change required several files to be updated besides the new file
hague.alt.c.

faq.md

@@ -88,6 +88,30 @@ some entries you should look at the original code as in `winner.orig.c` or
 `prog.orig.c`. Sometimes the original is in an alt version like `winner.alt.c`
 or `prog.alt.c`.
 
+## Q: Why have some entries that originally used `gets()` been modified to use `fgets()`? Doesn't this tamper with the entry too much?
+
+A fine line indeed has to be drawn here but it was decided that it is worth it
+because of alarming warnings that can be displayed, in some systems at runtime
+interspersed with the output of the program.
+
+For instance in macOS the entry [1990/tbr](1990/tbr/README.md) would output the
+warning in such a way that caused confusing output for the entry.
+
+In some cases this is not so easy to fix and in one case at least there is an
+alternate version that has the fix instead due to a problem it creates (correct
+output but segfaults after the output in one of the forms of input).
+
+In some cases it is not possible to fix or at least highly unlikely and so those
+have mainly not been touched except one that has had the buffer size increased
+(which could be done for others that are not possible to change to `fgets()` but
+this has not been done).
+
+In the future we, the judges, would prefer that entries use `fgets()` to prevent
+these problems.
+
+NOTE: due to 'compatibility reasons' `fgets()` stores the newline and `gets()`
+does not. We're not sure how this is compatibility but either way it can cause a
+problem and it is this that has complicated some fixes.
 
 ## Q: I cannot get entry XYZZY from year 19xx to compile!