Fix changelog entry for b836f810

Turns out passing type<string>() to Byref As String params wasn't affected
by the problem because astNewARG() uses a different code path for that.

Apparently it only happens with Byref As Any which is also what the
internally declared RTL functions often use (including fb_StrConcat()).
LLVM backend: Fix address-of

Re-use existing functions to simplify and handle additional cases.
ir: Always clear important IRVREG fields
LLVM backend: Fix negation self-UOP