[flang-commits] [flang] [llvm] [CMake] Fix using precompiled headers with ccache (PR #131397)

[Martin Storsjö via flang-commits]

mstorsjo wrote:

I find this change hard to get an overview of; you're both passing new options to ccache, and also changing how options are passed to ccache (previously only env variables, now both env vars and as command arguments, if I understand correctly?). Does this change need the change in how ccache options are passed? And can that change be split out from the functional change in passing more options wrt PCH, so that we first have a NFC change that only changes how ccache options are passed, followed by a potentially functional change in what options are passed?

https://github.com/llvm/llvm-project/pull/131397