Remove concat5 and concat6
Remove lval(), id() and wrap_variant() from builtin_functions.h
try without recursion

see if we don't need it
Remove some confusing assignments to NamedEntity::m_cachedClassOffset

Assigning this field is actually protected by the target
cache lock, and allocKnownClass does the assignment.
Get rid of variable break/continue

This is gone as of Zend 5.4: as far as I can tell, anything other than a
positive integer literal is a parse error (including constants, "1 + 1",
etc.) Let's get rid of it. The mere fact that this construct ever
existed in any programming language is deeply horrifying.

This lets us get rid of all the goofy code that subtracts 1 from the top
value on the stack, does IterFree if needed, and jumps to the next
level. Now, we can hardcode the necessary IterFrees and do a single
jump, right where the break/continue actually is.

The error message for using a non-integer expression is less helpful
than Zend's (Zend says "non-constant operand not supported"; ours is
"unexpected T_VARIABLE" or whatever). It wouldn't be that hard to do in
our parser, if we think that's helpful. I don't think it matters,
though.