always mangle local variables (#24681)

ref #24677

(cherry picked from commit 1af88a2d20)

tests/ccgbugs/tassign_nil_strings.nim

@@ -1,7 +1,7 @@
 discard """
   matrix: "--mm:refc"
   output: "Hello"
-  ccodecheck: "\\i@'a = ((NimStringDesc*) NIM_NIL)'"
+  ccodecheck: "\\i@'a_1 = ((NimStringDesc*) NIM_NIL)'"
 """
 
 proc main() =

tests/ccgbugs/tmissingvolatile.nim

@@ -1,7 +1,7 @@
 discard """
   output: "1"
   cmd: r"nim c --hints:on $options --mm:refc -d:release $file"
-  ccodecheck: "'NI volatile state;'"
+  ccodecheck: "'NI volatile state_1;'"
   targets: "c"
 """
 

tests/ccgbugs2/tcodegen.nim

@@ -45,3 +45,14 @@ block: # bug #22354
 
 
   main()
+
+proc main = # bug #24677
+  let NULL = 1
+  doAssert NULL == 1
+
+  var COMMA = 1
+  doAssert COMMA == 1
+
+  for NDEBUG in 0..2:
+    doAssert NDEBUG == NDEBUG
+main()