Fix fstack traces for macro nodes (#1318)

Since the lexer rewrite, MACRO nodes' fstack traces have not
included their parent REPT nodes' names.

test/asm/rept-macro-fstack-trace.asm

@@ -0,0 +1,41 @@
+MACRO outer
+  DEF it = 1
+  DEF n = 0
+  REPT 4
+    IF n % 2 == 0
+      IF DEF(inner)
+        PURGE inner
+      ENDC
+      DEF s EQUS "\nMACRO inner\nREPT 2\nREPT 2\nWARN \"round \{d:it\}\"\nDEF it += 1\nENDR\nENDR\nENDM"
+      s
+      PURGE s
+    ENDC
+    inner
+    DEF n += 1
+  ENDR
+ENDM
+REPT 1
+  outer
+ENDR
+
+MACRO foo
+  REPT 1
+    REPT 1
+      WARN "round {d:it}"
+      DEF it += 1
+    ENDR
+  ENDR
+ENDM
+REPT 1
+  REPT 1
+    MACRO bar
+      REPT 2
+        REPT 2
+          foo
+        ENDR
+      ENDR
+    ENDM
+    bar
+  ENDR
+ENDR
+