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_codegen_llvm/src/back/archive.rs

@@ -206,7 +206,7 @@ impl<'a> LlvmArchiveBuilder<'a> {
     }
 
     fn llvm_archive_kind(&self) -> Result<ArchiveKind, &str> {
-        let kind = &*self.config.sess.target.target.options.archive_format;
+        let kind = &*self.config.sess.target.options.archive_format;
         kind.parse().map_err(|_| kind)
     }