Fix fix on 1990/dds + make it use fgets()

The Makefile had -include stdio.h which made it fail to compile under
macOS (mismatch type of fopen()). I removed the prototype in the code.

I also made it use fgets() instead of gets() to make it safer.

1990/dds/README.md

@@ -14,14 +14,15 @@
 [Yusuke Endoh](/winners.html#Yusuke_Endoh) fixed this for modern systems. Thank
 you Yusuke!
 
+[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) removed the erroneous
+prototype to `fopen()` and made this use `fgets()` instead of `gets()` to make
+it safer. Thank you Cody for your assistance!
+
 ### To run
 
 	./dds
 
 
-NOTE: this entry uses `gets()` so you might get a warning when compiling and
-running this entry.
-
 ### Try:
 
 Give the following lines as input:
@@ -31,6 +32,8 @@ Give the following lines as input:
 
 NOTE: this is case sensitive.
 
+NOTE: this program will likely segfault if you specify a file that cannot be
+opened.
 
 ## Judges' comments: