If the glslopt pass fails to optimize a shader, we helpfully print the
shader source so that it is easy to find what the problem is. However,
we print this from within the build_parallel call, meaning if multiple
shaders fail to optimize we print all of their sources and they get
interleaved with each other, making it very difficult to find the
problematic line.
This patch makes us delay printing the source until the same place
where we print the error log, after we have stopped processing in
parallel. This means we will only print the source of a single
shader (the first one which fails to optimize), along with the error
log for that shader, which is much easier to debug.
This also includes a small tidy-up to handle both vertex and fragment
shaders in a loop to remove code duplication, and runs rustfmt.
Differential Revision: https://phabricator.services.mozilla.com/D169618
f03cafb885