ANDROID: x86: map CFI jump tables in pti_clone_entry_text

Allow CFI enabled entry code to make indirect calls by also mapping
CFI jump tables, and add a check to ensure the jump table section is
not empty.

Bug: 145297900
Change-Id: I1204c50a139ba62234f3bb4699c50921a831162b
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>