message: Uniformize access pattern to state.
  We seem to be using *& quite consistently across the codebase.
  Replacing 2 occurences of **.
  With this, `grep -R "\*\*" .` does not return instances of
  accesses  to state anymore.
diff: @@ -2651,8 +2651,8 @@ ParseResult ModuleParser::parseAffineMapDef() {
  StringRef affineMapId = getTokenSpelling().drop_front();
  // Check for redefinitions.
  - auto **entry = &getState().affineMapDefinitions[affineMapId];
  - if (*entry)
  + auto *&entry = getState().affineMapDefinitions[affineMapId];
  + if (entry)
  return emitError("redefinition of affine map id '" + affineMapId + "'");
  consumeToken(Token::hash_identifier);
  @@ -2662,8 +2662,8 @@ ParseResult ModuleParser::parseAffineMapDef() {
  "expected '=' in affine map outlined definition"))
  return ParseFailure;
  - *entry = parseAffineMapInline();
  - if (!*entry)
  + entry = parseAffineMapInline();
  + if (!entry)
  return ParseFailure;
  return ParseSuccess;
  @@ -2679,8 +2679,8 @@ ParseResult ModuleParser::parseIntegerSetDef() {
  StringRef integerSetId = getTokenSpelling().drop_front(2);
  // Check for redefinitions (a default entry is created if one doesn't exist)
  - auto **entry = &getState().integerSetDefinitions[integerSetId];
  - if (*entry)
  + auto *&entry = getState().integerSetDefinitions[integerSetId];
  + if (entry)
  return emitError("redefinition of integer set id '" + integerSetId + "'");
  consumeToken(Token::double_at_identifier);
  @@ -2690,8 +2690,8 @@ ParseResult ModuleParser::parseIntegerSetDef() {
  "expected '=' in outlined integer set definition"))
  return ParseFailure;
  - *entry = parseIntegerSetInline();
  - if (!*entry)
  + entry = parseIntegerSetInline();
  + if (!entry)
  return ParseFailure;
  return ParseSuccess;
  