rustc_codegen_llvm: Remove unused dependency rustc_incremental

Unused since commit f141acf
("Move finalize_session_directory call out of cg_llvm").

Author: joshtriplett

Cargo.lock

@@ -3715,7 +3715,6 @@ dependencies = [
  "rustc_errors",
  "rustc_fs_util",
  "rustc_hir",
- "rustc_incremental",
  "rustc_index",
  "rustc_llvm",
  "rustc_metadata",

compiler/rustc_codegen_llvm/Cargo.toml

@@ -23,7 +23,6 @@ rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_fs_util = { path = "../rustc_fs_util" }
 rustc_hir = { path = "../rustc_hir" }
-rustc_incremental = { path = "../rustc_incremental" }
 rustc_index = { path = "../rustc_index" }
 rustc_llvm = { path = "../rustc_llvm" }
 rustc_metadata = { path = "../rustc_metadata" }