add some missing LFS64 aliases for fadvise/fallocate functions
const-qualify the address argument to dladdr

this agrees with implementation practice on glibc and BSD systems, and
is the const-correct way to do things; it eliminates warnings from
passing pointers to const. the prototype without const came from
seemingly erroneous man pages.
eliminate explicit (long) casts when making syscalls

this practice came from very early, before internal/syscall.h defined
macros that could accept pointer arguments directly and handle them
correctly. aside from being ugly and unnecessary, it looks like it
will be problematic when we add support for 32-bit ABIs on archs where
registers (and syscall arguments) are 64-bit, e.g. x32 and mips n32.
fix argument types for legacy function inet_makeaddr

the type int was taken from seemingly erroneous man pages. glibc uses
in_addr_t (uint32_t), and semantically, the arguments should be
unsigned.
fix incorrect type for wd argument of inotify_rm_watch

this was wrong since the original commit adding inotify, and I don't
see any explanation for it. not even the man pages have it wrong. it
was most likely a copy-and-paste error.
remove sys/sysctl.h

this functionality has essentially always been deprecated in linux,
and was never supported by musl. the presence of the header was
reported to cause some software to attempt to use the nonexistant
function, so removing the header is the cleanest solution.
fix const-correctness in sigandset/sigorset arguments

this change is consistent with the corresponding glibc functions and
is semantically const-correct. the incorrect argument types without
const seem to have been taken from erroneous man pages.
fix signedness of pgoff argument to remap_file_pages

both the kernel and glibc agree that this argument is unsigned; the
incorrect type ssize_t came from erroneous man pages.
fix const-correctness of argument to stime

it's unclear what the historical signature for this function was, but
semantically, the argument should be a pointer to const, and this is
what glibc uses. correct programs should not be using this function
anyway, so it's unlikely to matter.