New header file missing from BUILD.gn

[aabdolrashidi]

Hello,
In a recent commit (1bc0e6f) , there is a new source file added for spvtools_opt in BUILD.gn: source/opt/invocation_interlock_placement_pass.cpp
However, its corresponding header file (invocation_interlock_placement_pass.h) is missing from the BUILD file. This causes presubmit failures when we want to roll the new commit into our repo.

CC: @cassiebeckley

[cassiebeckley]

Thanks for catching that! #5421 should fix this.

[aabdolrashidi]

Thank you for the fix!