[clang] [clang][driver] Support `--precompile` and `-fmodule-*` options in Clang-CL (PR #98761)

[Sharadh Rajaraman via cfe-commits]

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@@ -0,0 +1,65 @@
+// REQUIRES: system-windows
+
+// RUN: rm -rf %t
+// RUN: mkdir -p %t
+// RUN: split-file %s %t
+
+// RUN: %clang_cl /std:c++20 --precompile "%/t/Hello.cppm" "/Fo%/t/Hello.pcm"
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sharadhr wrote:

This outputs `Hello.pcm` in `<build path>\tools\clang\test\Driver` instead of in the temporary directory specified by `%t` and the next `RUN` command fails. I'm not the most familiar with the LLVM testing infrastructure; I'd like this to be reviewed.

https://github.com/llvm/llvm-project/pull/98761