[COFF, ARM64] Don't put jump table into a separate COFF section for EK_LabelDifference32

Windows ARM64 has PIC relocation model and uses jump table kind
EK_LabelDifference32. This produces jump table entry as
".word LBB123 - LJTI1_2" which represents the distance between the block
and jump table.

A new relocation type (IMAGE_REL_ARM64_REL32) is needed to do the fixup
correctly if they are in different COFF section.

This change saves the jump table to the same COFF section as the
associated code. An ideal fix could be utilizing IMAGE_REL_ARM64_REL32
relocation type.

Patch by Tom Tan!

Differential Revision: https://reviews.llvm.org/D57277

llvm-svn: 352465