Fix LLVM 3.3 build.

llvm/CallingConv.h was moved to folder llvm/IR.
Add missing pragma and deprecation warning.

The LDC_allow_inline pragma is not recognized. The deprecation message for
non-vendor pragmas is missing.
Fix prototypes from DMD2.

The prototypes for obj_includelib and obj_startaddress are DMD-specific.
Update them to match DMD 2.061.
Fix deprecation messages for non-vendor pragmas.

The deprecation message for non-vendor pragmas was never shown.