.bazelrc: pass ProgramData into action env, instead of hacking luajit build stuff

.bazelrc

@@ -1,2 +1,9 @@
 startup --windows_enable_symlinks
-build --enable_runfiles
+build --enable_runfiles
+
+# This is needed by cc::windows_registry::find_tool et. al. It calls out into a
+# MSVC COM DLL used to find MSVC installations, and that apparently relies on
+# the env var being set. For some reason, just doing --action_env=ProgramData
+# doesn't work, so we hardcode things to assume that it lives in C:\. We also
+# pollute non-Windows build envs with this, but whatever.
+build --action_env=ProgramData=C:\\ProgramData

third_party/cargo/vendor/luajit-src-210.1.3+restyfe08842/src/lib.rs

@@ -147,8 +147,6 @@ impl Build {
         msvcbuild.current_dir(build_dir.join("src"));
         msvcbuild.arg("static");
 
-        // HACK: without this, the MSVC COM DLL used to find cl.exe/link.exe/... fails.
-        std::env::set_var("ProgramData", "C:\\ProgramData");
         let cl = cc::windows_registry::find_tool(&target, "cl.exe").expect("failed to find cl");
         for (k, v) in cl.env() {
             msvcbuild.env(k, v);