Fix - CodeExtractor : Inherit Target Dependent Attributes from the parent function.

When extracting a set of blocks make sure to inherit all of the target
dependent attributes to make sure that the function will be valid for
lowering. One example is the "target-features" attribute for x86, if the
extracted region has functionality that relies on a specific feature it
will fail to be lowered.
This also allows for extracted functions to be valid for inlining, at
least back into the parent function, as the target attributes are tested
when inlining for compatibility.

Patch by River Riddle!

Differential Revision: https://reviews.llvm.org/D22713

llvm-svn: 277315