Move cg_ssa dependency fro rustc-main to rustc_driver

cc rust-lang#55864

Author: bjorn3

Cargo.lock

@@ -2114,7 +2114,6 @@ dependencies = [
 name = "rustc-main"
 version = "0.0.0"
 dependencies = [
- "rustc_codegen_ssa 0.0.0",
  "rustc_driver 0.0.0",
  "rustc_target 0.0.0",
 ]
@@ -2297,6 +2296,7 @@ dependencies = [
  "rustc-rayon 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_allocator 0.0.0",
  "rustc_borrowck 0.0.0",
+ "rustc_codegen_ssa 0.0.0",
  "rustc_codegen_utils 0.0.0",
  "rustc_data_structures 0.0.0",
  "rustc_errors 0.0.0",

src/librustc_driver/Cargo.toml

@@ -39,6 +39,10 @@ smallvec = { version = "0.6.5", features = ["union"] }
 syntax_ext = { path = "../libsyntax_ext" }
 syntax_pos = { path = "../libsyntax_pos" }
 
+# Make sure rustc_codegen_ssa ends up in the sysroot, because this
+# crate is intended to be used by codegen backends, which may not be in-tree.
+rustc_codegen_ssa = { path = "../librustc_codegen_ssa" }
+
 [dependencies.jemalloc-sys]
 version = '0.1.8'
 optional = true

src/rustc/Cargo.toml

@@ -11,9 +11,5 @@ path = "rustc.rs"
 rustc_target = { path = "../librustc_target" }
 rustc_driver = { path = "../librustc_driver" }
 
-# Make sure rustc_codegen_ssa ends up in the sysroot, because this
-# crate is intended to be used by codegen backends, which may not be in-tree.
-rustc_codegen_ssa = { path = "../librustc_codegen_ssa" }
-
 [features]
 jemalloc = ['rustc_driver/jemalloc-sys']