memory_erase() so far just called memset(), which the compiler might
optimize away under certain conditions if it feels there's benefit in
it. C11 knows a new memset_s() call that is like memset(), but may not
be optimized away. Ideally, we'd just use that call, but glibc currently
does not support it. Hence, implement our own simplistic version of it.
We use a GCC pragma to turn off optimization for this call, and also use
the "volatile" keyword on the pointers to ensure that gcc will use the
pointers as-is. According to a variety of internet sources, either one
does the trick. However, there are also reports that at least the
volatile thing isn't fully correct, hence let's add some snake oil and
employ both techniques.
https://news.ycombinator.com/item?id=4711346
There are more than enough calls doing string manipulations to deserve
its own files, hence do something about it.
This patch also sorts the #include blocks of all files that needed to be
updated, according to the sorting suggestions from CODING_STYLE. Since
pretty much every file needs our string manipulation functions this
effectively means that most files have sorted #include blocks now.
Also touches a few unrelated include files.
Lennart Poettering