Windows CI optimization: fix sscache usage (currently not used?)

[ssalonen]

Bug description

Github CI shows that sccache is not used at all on Windows. This is despite the efforts to command rustc and cmake to use sccache in https://github.com/ssalonen/libcec-sys/pull/44

Output from sccache action:

Post job cleanup.
C:\hostedtoolcache\windows\sccache\0.5.4\x64\sccache.exe --show-stats
Compile requests                      0
Compile requests executed             0
Cache hits                            0
Cache misses                          0
Cache timeouts                        0
Cache read errors                     0
Forced recaches                       0
Cache write errors                    0
Compilation failures                  0
Cache errors                          0
Non-cacheable compilations            0
Non-cacheable calls                   0
Non-compilation calls                 0
Unsupported compiler calls            0
Average cache write               0.000 s
Average compiler                  0.000 s
Average cache read hit            0.000 s
Failed distributed compilations       0
Cache location                  Local disk: "C:\\Users\\runneradmin\\AppData\\Local\\Mozilla\\sccache\\cache"
Version (client)                0.5.4

To Reproduce

Run CI

Expected behavior

To see compile requests and cache numbers on windows

Screenshots

Environment

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Additional context

[ssalonen]

Related

https://github.com/mozilla/sccache/issues/1097 https://github.com/hendrikmuhs/ccache-action/issues/100