Incorrect FileCheck path on msvc and RelWithDbgInfo

[TimNN]

When compiling for msvc and using a RelWithDbgInfo LLVM, an incorrect path to FileCheck.exe is used (hardcoded to Release/bin).

I find the exact conditions which determine the directory to use a bit confusing.

[alexcrichton]

I also find the directory layout of an LLVM build confusing ;_;

[wesleywiser]

Looks like this was fixed in #50961.

rust/src/bootstrap/lib.rs

Lines 803 to 815 in 256721e

	let base = if !self.ninja() && self.config.build.contains("msvc") {
	if self.config.llvm_optimize {
	if self.config.llvm_release_debuginfo {
	base.join("RelWithDebInfo")
	} else {
	base.join("Release")
	}
	} else {
	base.join("Debug")
	}
	} else {
	base
	};