vmlinux.lds.h: Add .symtab, .strtab, and .shstrtab to ELF_DETAILS

When linking vmlinux with LLD, the synthetic sections .symtab, .strtab,
and .shstrtab are listed as orphaned. Add them to the ELF_DETAILS section
so there will be no warnings when --orphan-handling=warn is used more
widely. (They are added above comment as it is the more common
order[1].)

ld.lld: warning: <internal>:(.symtab) is being placed in '.symtab'
ld.lld: warning: <internal>:(.shstrtab) is being placed in '.shstrtab'
ld.lld: warning: <internal>:(.strtab) is being placed in '.strtab'

[1] https://lore.kernel.org/lkml/20200622224928.o2a7jkq33guxfci4@google.com/

Reported-by: Fangrui Song <maskray@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: linux-arch@vger.kernel.org
Link: https://lore.kernel.org/r/20200821194310.3089815-6-keescook@chromium.org