Remove (lots of) dead code

Found with https://github.com/est31/warnalyzer.

Dubious changes:
- Is anyone else using rustc_apfloat? I feel weird completely deleting
  x87 support.
- Maybe some of the dead code in rustc_data_structures, in case someone
  wants to use it in the future?
- Don't change rustc_serialize

  I plan to scrap most of the json module in the near future (see
  https://github.com/rust-lang/compiler-team/issues/418) and fixing the
  tests needed more work than I expected.

TODO: check if any of the comments on the deleted code should be kept.

1 files changed, 0 insertions, 10 deletions

diff --git a/compiler/rustc_errors/src/snippet.rs b/compiler/rustc_errors/src/snippet.rs
index acb88e57db5..3fe02bd0cee 100644
--- a/compiler/rustc_errors/src/snippet.rs
+++ b/compiler/rustc_errors/src/snippet.rs
@@ -121,16 +121,6 @@ impl Annotation {
         matches!(self.annotation_type, AnnotationType::MultilineLine(_))
     }
 
-    pub fn is_multiline(&self) -> bool {
-        matches!(
-            self.annotation_type,
-            AnnotationType::Multiline(_)
-                | AnnotationType::MultilineStart(_)
-                | AnnotationType::MultilineLine(_)
-                | AnnotationType::MultilineEnd(_)
-        )
-    }
-
     pub fn len(&self) -> usize {
         // Account for usize underflows
         if self.end_col > self.start_col {