Replace target.target with target and target.ptr_width with target.pointer_width

Preparation for a subsequent change that replaces
rustc_target::config::Config with its wrapped Target.

On its own, this commit breaks the build. I don't like making
build-breaking commits, but in this instance I believe that it
makes review easier, as the "real" changes of this PR can be
seen much more easily.

Result of running:

find compiler/ -type f -exec sed -i -e 's/target\.target\([)\.,; ]\)/target\1/g' {} \;
find compiler/ -type f -exec sed -i -e 's/target\.target$/target/g' {} \;
find compiler/ -type f -exec sed -i -e 's/target.ptr_width/target.pointer_width/g' {} \;
./x.py fmt

compiler/rustc_metadata/src/dependency_format.rs

@@ -127,7 +127,7 @@ fn calculate_type(tcx: TyCtxt<'_>, ty: CrateType) -> DependencyList {
         if ty == CrateType::Staticlib
             || (ty == CrateType::Executable
                 && sess.crt_static(Some(ty))
-                && !sess.target.target.options.crt_static_allows_dylibs)
+                && !sess.target.options.crt_static_allows_dylibs)
         {
             for &cnum in tcx.crates().iter() {
                 if tcx.dep_kind(cnum).macros_only() {