Failure to build with sccache on Windows

[Redfire75369]

rust-mozjs (specifically jsglue.cpp) fails to build on Windows with sccache.
I have tested, and it has successfully built on Linux (WSL Debian).

Setup

1. Install sccache (v0.2.15)
2. Run set RUSTC_WRAPPER=sccache, and sccache --start-server
3. Run cargo clean --release
4. Run cargo build --release -vv > build.log

Actual Output: https://paste.gg/p/redfire/2c9d5dd64f724e8b806a8175653d75e5
(Expected Output is like 65K lines...)

I think I have narrowed it down to the build command for building jsglue.cpp.
Expected jsglue.cpp build command flags (No sccache):

[mozjs 0.14.1] running: "clang-cl.exe" "-nologo" "-MD" "-O2" "-Brepro" "-m64" "-I" "C:\\Users\\Redfire\\software\\github\\rust-mozjs\\target\\release\\build\\mozjs_sys-389741e052a7c073\\out\\build\\dist\\include" "-W4" "-DSTATIC_JS_API" "-FIC:\\Users\\Redfire\\software\\github\\rust-mozjs\\target\\release\\build\\mozjs_sys-389741e052a7c073\\out\\build\\js\\src\\js-confdefs.h" "-Zi" "-GR-" "-std:c++17" "-Wno-c++0x-extensions" "-Wno-return-type-c-linkage" "-Wno-invalid-offsetof" "-Wno-unused-parameter" "-DWIN32=" "-FoC:\\Users\\Redfire\\software\\github\\rust-mozjs\\target\\release\\build\\mozjs-20879d0ed8d587aa\\out\\src/jsglue.o" "-c" "src/jsglue.cpp"

Actual jsglue.cpp build command flags (w/ sccache):

[mozjs_sys 0.68.2] running: "sccache" "clang-cl.exe" "-nologo" "-MD" "-O2" "-Brepro" "-m64" "-I" "C:\\Users\\Redfire\\software\\github\\rust-mozjs\\target\\release\\build\\mozjs_sys-389741e052a7c073\\out\\build\\dist/include" "-I" "C:\\Users\\Redfire\\software\\github\\rust-mozjs\\target\\release\\build\\mozjs_sys-389741e052a7c073\\out\\build\\js/src" "-W4" "-FI" "C:\\Users\\Redfire\\software\\github\\rust-mozjs\\target\\release\\build\\mozjs_sys-389741e052a7c073\\out\\build/js/src/js-confdefs.h" "-FoC:\\Users\\Redfire\\software\\github\\rust-mozjs\\target\\release\\build\\mozjs_sys-389741e052a7c073\\out\\build\\glue\\src/jsglue.o" "-c" "src/jsglue.cpp"

Edit:
After looking around a bit, it seems that build.rs is being completely skipped, look at the flags that are missing. https://github.com/servo/rust-mozjs/blob/master/build.rs

[jdm]

This sounds like an issue that should be filed against sccache instead.