Fix jpeg "uninitialized pointer" linking error

When linking to jpeg.lib, compiler returned "error C4703: potentially
uninitialized local pointer variable used". This commit fixes the issue.

Verification:
    Batch build nfEngineDeps and use nfCommon library to test if linking
    jpeg.lib is successful.

Change-Id: Id539a2b1c12e3a11434d4337fed09e7aed17d0b0