Fix a rare corner case bug which exposed a serious block API generation

Fix a rare corner case bug which exposed a serious block API generation
when initialized variable is a byref block variable and is referenced recursively
in the initializer (you guessed it, it is block implementation of
fibonacci number). Fix, on the other hand is trvial, by generating the
API for byref variable before API for its initializer. We will have this
test added to our internal test suite as a clang-style test is not possible
due to very convoluted IR sequence. Fixes radar 7745514.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@98393 91177308-0d34-0410-b5e6-96231b3b80d8