[clang] [Driver] Improve error when a compiler-rt library is not found (PR #81037)

[Fangrui Song via cfe-commits]

================
@@ -44,9 +43,8 @@
 // CHECK-V6M-DEFAULTCXX: "-resource-dir" "[[RESOURCE_DIR:[^"]+]]"
 // CHECK-V6M-DEFAULTCXX: ld{{(.exe)?}}" "{{.*}}.o" "-Bstatic" "-EL"
 // CHECK-V6M-DEFAULTCXX-SAME: "-L{{[^"]*}}{{[/\\]+}}Inputs{{[/\\]+}}baremetal_arm{{[/\\]+}}lib"
-// CHECK-V6M-DEFAULTCXX-SAME: "-L[[RESOURCE_DIR]]{{[/\\]+}}lib{{[/\\]+}}baremetal"
 // CHECK-V6M-DEFAULTCXX-SAME: "-lc++" "-lc++abi" "-lunwind"
-// CHECK-V6M-DEFAULTCXX-SAME: "-lc" "-lm" "-lclang_rt.builtins-armv6m" "--target2=rel" "-o" "a.out"
----------------
MaskRay wrote:

There are a few places where I delete `-L` of the directory containing `libclang_rt.*` files. I think it is correct. This `-L` is not useful.

https://github.com/llvm/llvm-project/pull/81037