compiler: Set actual initializer for global variables

In the Go SSA, global variables are initialized in the init() function
instead of declaring them in the global itself. Work around this oddity
by simply setting the correct initializer when we find this global.

This should produce more efficient code, both in RAM and code size.
Apparently LLVM didn't optimize it away on it's own.

tgo.go

@@ -583,7 +583,11 @@ func (c *Compiler) parseInstr(frame *Frame, instr ssa.Instruction) error {
 		if err != nil {
 			return err
 		}
-		c.builder.CreateStore(val, addr)
+		if instr.Parent().Synthetic == "package initializer" {
+			addr.SetInitializer(val)
+		} else {
+			c.builder.CreateStore(val, addr)
+		}
 		return nil
 	default:
 		return errors.New("unknown instruction: " + fmt.Sprintf("%#v", instr))