bistro/bistro/processes/TaskSubprocessQueue.cpp: fix shadow error
bistro/bistro/processes/TaskSubprocessQueue.cpp: fix shadow error

Summary:
Fix errors exposed by gcc's -Wshadow-compatible-local.
See https://fburl.com/bad-shadow for justification.
I'm now removing the exemptions. See T25277067.

Rename inner "opts" to "options".

This avoids the following errors:

  bistro/bistro/processes/TaskSubprocessQueue.cpp:413:7: error: declaration of 'opts' shadows a previous local [-Werror=shadow-compatible-local]

Reviewed By: yfeldblum

Differential Revision: D6771705

fbshipit-source-id: 942a02afeaeb603b32c97a5e35a72af756efbc50

facebook/bistro,facebook/bistro,facebook/bistro,facebook/bistro,facebook/bistro,facebook/bistro