unified the block endings

test_read_file.sl

@@ -8,24 +8,24 @@ import stdlib/io.sl
         write_buf             # print file contents (file_len file_addr)
         0
         exit
-    then
+    end
     dup -2 == if              # open() failed
         drop
         "open() failed: errno=" puts
         swap puti cr
         exit
-    then
+    end
     dup -1 == if              # fstat() failed
         drop
         "fstat() failed: errno=" puts
         swap puti cr
         exit
-    then
+    end
     dup -3 == if              # mmap() failed
         drop
         "mmap() failed" puts
         exit
-    then
+    end
     "unknown read_file failure" puts
     dup                       # file_len file_len file_addr
     exit                       # Exit with returned file_len as the program exit code (debug)