spirv: Emit "continue" when the switch case is a loop's continue block
Previously no actual jump was emitted because cse->body
is empty for such cases.
Fixes: 9c2a1143 ("spirv: Rewrite CFG construction") Closes: #6729 (closed) Signed-off-by: Sviatoslav Peleshko sviatoslav.peleshko@globallogic.com