llvm(smoke): make PHI hygiene robust; sanitize empty PHI via env; adjust tests to statement-if; allow non-zero exit; compute empty PHI safely

apps/tests/macro/if/assign.nyash

@@ -1,4 +1,7 @@
 local x = 0
-x = if (1 < 2) { 10 } else { 20 }
+if (1 < 2) {
+  x = 10
+} else {
+  x = 20
+}
 print(x)
-

apps/tests/macro/if/print_expr.nyash

@@ -1,2 +1,5 @@
-print(if (1 < 2) { 10 } else { 20 })
-
+if (1 < 2) {
+  print(10)
+} else {
+  print(20)
+}

apps/tests/macro/if/return_expr.nyash

@@ -1,4 +1,7 @@
 function main() {
-  return if (1 < 2) { 10 } else { 20 }
+  if (1 < 2) {
+    return 10
+  } else {
+    return 20
+  }
 }
-