Preserve exceptions information during calls code generation.

Preserve exceptions information during calls code generation.

This patch changes the generation of CGFunctionInfo to contain
the FunctionProtoType if it is available. This enables the code
generation for call instructions to look into this type for
exception information and therefore generate better quality
IR - it will not create invoke instructions for functions that
are know not to throw.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@253926 91177308-0d34-0410-b5e6-96231b3b80d8