buildSymbols
Reverse-remap the runtime jar through cached mappings into a mojmap symbol jar: the half of the bundle the loader's binpatches are baked into, and the only half a loader change rebuilds — locally, without the network.
Parameters
mcUri
CodeSource URI of the runtime Minecraft jar — the LOADER's view of it, so on FML a union: URI whose overlaid binpatches are part of what gets reverse-remapped
mappings
the mappings assembleMappings wrote; its extension picks the provider
outSymbolsDir
output directory for the generated mojmap symbol jar and its deps.txt
Throws
if masking-loader init or the remap fails