Bump to 2019-06-22 to get fix from upstream

We need commit
d46a373b391cb546f5a737fd5009f7733c220531 (rust-lang/rust#61959)
to avoid a compiler ICE when using simd builtins.

c2rust-refactor/src/context.rs

@@ -425,14 +425,14 @@ impl<'a, 'tcx> RefactorCtxt<'a, 'tcx> {
 
     /// Attempt to resolve a `Use` item to the `hir::Path` of the imported item. The
     /// given item _must_ be a `Use`.
-    pub fn resolve_use(&self, u: &Item) -> P<hir::Path> {
+    pub fn resolve_use(&self, u: &Item) -> &P<hir::Path> {
         let hir_node = self
             .hir_map()
             .find(u.id)
             .unwrap_or_else(|| panic!("Couldn't find HIR node for {:?}", u));
         let hir_item = expect!([hir_node] hir::Node::Item(i) => i);
         let path = expect!([&hir_item.node] hir::ItemKind::Use(path, _) => path);
-        path.clone()
+        path
     }
 
     /// Compare two items for internal structural equivalence, ignoring field names.

rust-toolchain

@@ -1 +1 @@
-nightly-2019-06-20
+nightly-2019-06-22

scripts/common.py

@@ -97,7 +97,7 @@ class Config:
     MIN_PLUMBUM_VERSION = (1, 6, 3)
     CC_DB_JSON = "compile_commands.json"
 
-    CUSTOM_RUST_NAME = 'nightly-2019-06-20'
+    CUSTOM_RUST_NAME = 'nightly-2019-06-22'
 
     """
     Reflect changes to all configuration variables that depend on LLVM_VER