Make 1987/wall use fgets() not gets()

Added in README.md a diff so one can see how it was done.

1987/wall/README.md

@@ -9,6 +9,17 @@ Panorama City, CA  91402  USA
 
         make all
 
+[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) made this entry safer
+by changing `gets()` to `fgets()`. Thank you Cody for your assistance! If you
+wish for the original unsafe version you can make the following change:
+
+	-signal())();char*V,cm,D['x'],M='\n',I;L(MV,V,(c+='d',ix))m(x){v)
+	+signal())();char*V,cm,D['x'],M='\n',I,*gets();L(MV,V,(c+='d',ix))m(x){v)
+	 signal(X/'I',vi[x]);}d(x)char*x;{v)write(i,x,i);}L(MC,V,M+I)xv(){c>=i?m(
+	 c/M/M+M):(d(&M),m(cm));}L(mi,V+cm,M)L(md,V,M)MM(){c=c*M%X;V-=cm;m(ix);}
+	-LXX(){fgets(D,'x',stdin)||(vi[iv])();c=atoi(D);while(c>=X){c-=X;d("m");}V="ivxlcdm"
+	+LXX(){gets(D)||(vi[iv])();c=atoi(D);while(c>=X){c-=X;d("m");}V="ivxlcdm"	
+
 ## To run: