fixes unnamed block generated invalid C code

[ringabout]

Otherwise it gives a C error

nimcache/tes8193z1.c:433:3: error: 'break' statement not in loop or switch statement
  433 |   break;}
      |   ^

[Araq]

An unnamed break to exist from a block is valid code though, you cannot simply disallow it.

[ringabout]

Okay, but it's already a deprecated warning in Nim, I can try to make it work and produce a warning

[Araq]

We don't really have any infrastructure for warnings and it wouldn't change the fact that it's a compiler bug we need to fix.