Fix missing gflags shlwapi dependency on MinGW.
Fix missing gflags shlwapi dependency on MinGW.

- Reported by Simeon (s1m3mu3@gmail.com) on Ceres mailing list.

Change-Id: If23491128fb6320d9b643eb3d5db7d9e67ffcf0b

whuaegeanse/ceres-solver,DougFirErickson/ceres-solver,DougFirErickson/ceres-solver,whuaegeanse/ceres-solver,ysonggit/ceres-solver,ysonggit/ceres-solver,ysonggit/ceres-solver,DougFirErickson/ceres-solver,whuaegeanse/ceres-solver,DougFirErickson/ceres-solver,ysonggit/ceres-solver,whuaegeanse/ceres-solver