Avoid error:
```
kernel/mem.cc:1683:7: error: conflicting declaration ‘using addr_t = using addr_t = uint32_t’
1683 | using addr_t = MemContents::addr_t;
| ^~~~~~
In file included from /usr/include/sys/types.h:222,
from /usr/include/pthread.h:11,
from /usr/lib/gcc/x86_64-pc-cygwin/12/include/c++/x86_64-pc-cygwin/bits/gthr-default.h:35,
from /usr/lib/gcc/x86_64-pc-cygwin/12/include/c++/x86_64-pc-cygwin/bits/gthr.h:148,
from /usr/lib/gcc/x86_64-pc-cygwin/12/include/c++/ext/atomicity.h:35,
from /usr/lib/gcc/x86_64-pc-cygwin/12/include/c++/bits/cow_string.h:37,
from /usr/lib/gcc/x86_64-pc-cygwin/12/include/c++/bits/basic_string.h:51,
from /usr/lib/gcc/x86_64-pc-cygwin/12/include/c++/string:53,
from ./kernel/yosys_common.h:27,
from ./kernel/yosys.h:42,
from ./kernel/mem.h:23,
from kernel/mem.cc:20:
/usr/include/machine/types.h:63:15: note: previous declaration as ‘typedef char* addr_t’
63 | typedef char *addr_t;
```
According to IntelliSense, only the return types need to be prefixed with `MemContents::`, the rest are automagically using the class definition and highlight as `using Yosys::MemContents::addr_t = uint32_t`.
`Const::size()` returns int, so change iterators that use it to `auto` instead of `size_t`.
For cases where size is being explicitly cast to `int`, use the wrapper that we already have instead: `Yosys::GetSize()`.
There's a mismatch between what `kernel/mem.cc` emits for memories
with no read ports and what the internal RTLIL check expects.
The point of dispute it whether some of the parameters relating to read
ports have a zero-width value in this case. The `mem.cc` code says no,
the internal checker says yes.
Surveying the other `$mem_v2` parameters, and internal cell parameters
in general, I am inclined to side with the `mem.cc` code.
This breaks RTLIL compatibility but for an obscure edge case.
Initialize "unsigned int inner" in hash() functions
Includes a log_assert() that might help catch corrupted data structures
or future incomplete modification of DriveType definition
