Fix 1985/applin under macOS

The solution is a curious one that I should have known. It wasn't even a
change in the code itself; rather in macOS one needs to include unistd.h
as with macOS without a proper prototype at least some functions do not
work right. This showed itself in 1984/anonymous as well though I had to
do a bit more to fix that one - provide a prototype in the code
(including the header file did not work - this was documented at one
point in the README.md and possibly bugs.md) and change the code
slightly as well. Ironically this was figured out through linux! See
bugs.md as I updated the on warnings section - this was an example entry
where some warnings are worth fixing.

1985/applin/Makefile

@@ -61,7 +61,7 @@ CDEFINE=
 
 # Include files that are needed to compile
 #
-CINCLUDE=
+CINCLUDE= -include unistd.h
 
 # Optimization
 #

1985/applin/README.md

@@ -16,9 +16,14 @@ make all
 ```
 
 NOTE: [Yusuke Endoh](/winners.html#Yusuke_Endoh) provided a patch to get this to
-not issue a bus error. Thank you Yusuke! [Cody Boone
-Ferguson](/winners.html#Cody_Boone_Ferguson) noted that this entry does not work
-under macOS. Try it out and see for yourself what happens!
+not issue crash and [Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson)
+fixed this to work with macOS.  The problem with the crash is that it
+destructively rewrites string literals but with `strdup()` it's safe. For macOS
+it's because there was no prototype for `execlp()` and macOS has problems with
+missing prototypes for some functions (this was also seen when Cody fixed
+[1984/anonymous](/1984/anonymous/anonymous.c) for macOS as well though that fix
+was more complicated). Ironically this fix was discovered through linux! Thank
+you Yusuke and Cody for your help!
 
 
 ## Judges' remarks: