transforms.llvm_ir_generator: accept delay instructions.

The delay instruction is just like a branch (discontinuity
in instruction flow), but it also carries metadata: how long
did the execution of its basic block take. This metadata only
matters during inlining and interleaving, so we treat it here
as a mere branch.

artiq/compiler/transforms/llvm_ir_generator.py

@@ -1068,6 +1068,8 @@ class LLVMIRGenerator:
     def process_Branch(self, insn):
         return self.llbuilder.branch(self.map(insn.target()))
 
+    process_Delay = process_Branch
+
     def process_BranchIf(self, insn):
         return self.llbuilder.cbranch(self.map(insn.condition()),
                                       self.map(insn.if_true()), self.map(insn.if_false()))