[ExecutionEngine] Correct the size of a write in a COFF i386 relocation

We want to be writing a 32bit value, so we should be writing 4 bytes
instead of 2.

Patch by Alex Langford <apl@fb.com>.

Differential Revision: https://reviews.llvm.org/D38872

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315964 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed