Remove alt target from TARGETS in 1998/schweikh2

This is because it doesn't compile in all systems though it is supposed
to I think.

1998/schweikh2/README.md

@@ -13,9 +13,9 @@
 
         make all
 
-	NOTE: Almost every compiler is supposed to be able to accept the code in
-	schweikh2.c; try compiling schweikh2.alt.c to see if your compiler
-	is fully standard-compliant.
+NOTE: Almost every compiler is supposed to be able to accept the code in
+schweikh2.c; try compiling schweikh2.alt.c to see if your compiler
+is fully standard-compliant.
 
 ### To run