Wrong permissions for non-STT_FUNC symbols in executable sections

The Morello-specific getPermissions in lld/ELF/Arch/Cheri.cpp, used by both MorelloCapRelocsSection and getMorelloSizeAndPermissions, bogusly uses SHF_EXECINSTR of the containing section to determine whether or not a non-STT_FUNC symbol should be made executable. This is wrong and deviates from the correct semantics provided by the existing CHERI LLVM CheriCapRelocsSection; only STT_FUNC symbols should be executable, data (which conservatively includes STT_NOTYPE) should not be, even if in .text, as that makes constant pools executable.