CFGFast: initialize uninitialized register values on demand in _resolve_jump_table_fast().
CFGFast: initialize uninitialized register values on demand in _resolve_jump_table_fast().

Consider the following assembly snippet:

// rdi is uninitialized
mov rax, qword ptr [rdi]
mov rbx, qword ptr [rdi]

Previously since rdi is uninitialized, rax and rbx will have two
different unconstrained values. However, since rdi is not changed, they
should have the same unconstrained value.

This commit fixes this issue by initializing the uninitialized rdi to
some concrete value at the first time it is used as a memory address for
a memory read. It is somewhat similar to UCSE.

tyb0807/angr,tyb0807/angr,angr/angr,tyb0807/angr,chubbymaggie/angr,chubbymaggie/angr,iamahuman/angr,schieb/angr,axt/angr,angr/angr,iamahuman/angr,axt/angr,axt/angr,schieb/angr,f-prettyland/angr,schieb/angr,f-prettyland/angr,iamahuman/angr,f-prettyland/angr,angr/angr,chubbymaggie/angr