scripts/mksysmap: Ignore prefixed KCFI symbols

scripts/mksysmap: Ignore prefixed KCFI symbols

The (relatively) new KCFI feature in LLVM/Clang encodes type information
for C functions by generating symbols named __kcfi_typeid_<fname>, which
can then be referenced from assembly. However, some custom build rules
(e.g. nVHE or early PIE on arm64) use objcopy to add a prefix to all the
symbols in their object files, making mksysmap's ignore filter miss
those KCFI symbols.

Therefore, explicitly list those twice-prefixed KCFI symbols as ignored.

Alternatively, this could also be achieved in a less verbose way by
ignoring any symbol containing the string "__kcfi_typeid_". However,
listing the combined prefixes explicitly saves us from running the small
risk of ignoring symbols that should be kept.

Signed-off-by: Pierre-Clément Tosi <ptosi@google.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>