Add madvise flag which performs a best-effort synchronous
collapse of the native pages mapped by the memory range
into Transparent Huge Pages (THPs)
see
  linux commit 7d8faaf155454f8798ec56404faca29a82689c77
  mm/madvise: introduce MADV_COLLAPSE sync hugepage collapse

this flag works like MADV_DONTNEED but also applies to locked memory
ranges.

see
  linux commit 9457056ac426e5ed0671356509c8dcce69f8dee0
  mm: madvise: MADV_DONTNEED_LOCKED

Add madvise flags to populate(prefault) page tables
see
  linux commit 4ca9b3859dac14bbef0c27d00667bb5b10917adb
  mm/madvise: introduce MADV_POPULATE_(READ|WRITE) to prefault page tables

These new LoongArch reloc types(101 to 126) have been added in
LoongArch psABI v2.30 and NT_LOONGARCH_HW_BREAK/NT_LOONGARCH_HW_WATCH
sync with Linux 6.12 elf.h.

v4-compatible addresses in ipv6 are a deprecated feature where the
high 96 bits are all zero and an ipv4 address is stored in the low
32 bits. however, since :: and ::1 are the unspecified and loopback
addresses, these two particular values are excluded from the
definition of the v4-compat class.

our version of the macro incorrectly assessed this condition by
checking only the high 96 and low 8 bits. this incorrectly excluded
the v4compat version of any ipv4 address ending in .1, not just ::1.

rather than writing out non-obvious or error-prone conditions on the
individual address bytes, just express the "not :: or ::1" condition
naturally using the existing IN6_IS_ADDR_UNSPECIFIED and
IN6_IS_ADDR_LOOPBACK macros, after checking that the high 96 bits are
all zero. any vaguely reasonable compiler will collapse out the
redundant tests of the upper bits as part of CSE.

there are probably more new auxv keys that should be added, but these
are added now specifically because we may need to mask them.

As of Linux 6.11, these fields and mask macros have been added to
include/uapi/linux/stat.h.

we have the cpuset macros call calloc/free/memset/memcmp directly so
that they don't depend on any further ABI surface. this is not
namespace-clean, but only affects the _GNU_SOURCE feature profile,
which is not intended to be namespace-clean. nonetheless, reports come
up now and then of things which are gratuitously broken, usually when
an application has wrapped malloc with macros.

this patch parenthesizes the function names so that function-like
macros will not be expanded, and removes the unused declaration of
memcpy. this is not a complete solution, but it should improve things
for affected applications, particularly ones which are not even trying
to use the cpuset interfaces which got them just because g++ always
defines _GNU_SOURCE.