langref: update grammar with c pointers

See #1059

doc/langref.html.in

@@ -8164,7 +8164,8 @@ ArrayTypeStart <- LBRACKET Expr? RBRACKET
 PtrTypeStart
     <- ASTERISK
      / ASTERISK2
-     / LBRACKET ASTERISK RBRACKET
+     / PTRUNKNOWN
+     / PTRC
 
 # ContainerDecl specific
 ContainerDeclAuto <- ContainerDeclType LBRACE ContainerMembers RBRACE
@@ -8262,7 +8263,7 @@ LARROW2              <- '<<'     ![=]      skip
 LARROW2EQUAL         <- '<<='              skip
 LARROWEQUAL          <- '<='               skip
 LBRACE               <- '{'                skip
-LBRACKET             <- '['                skip
+LBRACKET             <- '['      ![*]      skip
 LPAREN               <- '('                skip
 MINUS                <- '-'      ![%=>]    skip
 MINUSEQUAL           <- '-='               skip
@@ -8279,6 +8280,8 @@ PLUS2                <- '++'               skip
 PLUSEQUAL            <- '+='               skip
 PLUSPERCENT          <- '+%'     ![=]      skip
 PLUSPERCENTEQUAL     <- '+%='              skip
+PTRC                 <- '[*c]'             skip
+PTRUNKNOWN           <- '[*]'              skip
 QUESTIONMARK         <- '?'                skip
 RARROW               <- '>'      ![>=]     skip
 RARROW2              <- '>>'     ![=]      skip

src/parser.cpp

@@ -2778,8 +2778,8 @@ static AstNode *ast_parse_array_type_start(ParseContext *pc) {
 // PtrTypeStart
 //     <- ASTERISK
 //      / ASTERISK2
-//      / LBRACKET ASTERISK RBRACKET
-//      / LBRACKET ASTERISK C RBRACKET
+//      / PTRUNKNOWN
+//      / PTRC
 static AstNode *ast_parse_ptr_type_start(ParseContext *pc) {
     Token *asterisk = eat_token_if(pc, TokenIdStar);
     if (asterisk != nullptr) {