Add dummy macros for conditionally defined macros

[lumynou5]

Some macros are conditionally defined, such as list_for_each_entry_safe, which is only defined if typeof is supported. CppCheck reports unknownMacro when these macros are used because it checks each branch of conditional compilation (as the --force option presents) and they are not always defined.

A possible solution is to define dummy macros to bypass the static analytics:

#if __LIST_HAVE_TYPEOF
#define list_for_each_entry_safe(entry, safe, head, member)            \
    for (entry = list_entry((head)->next, typeof(*entry), member),     \
        safe = list_entry(entry->member.next, typeof(*entry), member); \
         &entry->member != (head); entry = safe,                       \
        safe = list_entry(safe->member.next, typeof(*entry), member))
#else
#define list_for_each_entry_safe(entry, safe, head, member)            \
    for (entry = safe = (void *) 1;                                    \
         sizeof(struct { int : -1; });                                 \
         ++(entry), ++(safe))
#endif

The assignments and increments make CppCheck consider the variables are used and suppress potential reports about uninitialized variables, unused variables, and can-be-constant variables. The pointers with value 1 instead of NULL suppress reports about dereferencing null pointers.

This way, code can pass the static analytics without changes to the macro parameters.