Move the dataflow framework to its own crate.

compiler/rustc_mir_transform/src/coverage/spans.rs

@@ -1,15 +1,13 @@
 use super::debug::term_type;
 use super::graph::{BasicCoverageBlock, BasicCoverageBlockData, CoverageGraph, START_BCB};
 
-use crate::util::spanview::source_range_no_file;
-
 use rustc_data_structures::graph::WithNumNodes;
+use rustc_middle::mir::spanview::source_range_no_file;
 use rustc_middle::mir::{
     self, AggregateKind, BasicBlock, FakeReadCause, Rvalue, Statement, StatementKind, Terminator,
     TerminatorKind,
 };
 use rustc_middle::ty::TyCtxt;
-
 use rustc_span::source_map::original_sp;
 use rustc_span::{BytePos, ExpnKind, MacroKind, Span, Symbol};