Implement diffing individual data symbols (#244)

* Implement diffing individual data symbols

* Remove unused code for diffing sections

* Data diff view: Make rows show offset within the symbol, not within the section

* Remove SelectedSymbol enum as it only has a single variant now

* Create fake data section symbols to allow diffing entire sections again

* Fix text sections not having their size zeroed out

* Update test snapshots

* Clean up code for inferring section symbol size

* Fix bug where PPC pool references weren't ignoring section symbols

* Update comment

* Always add unique section symbols for data sections

* Update test snapshots

* Remove unnecessary clone in format! call

* Auto-start mapping for unpaired data symbols

objdiff-cli/src/cmd/report.rs

@@ -9,7 +9,7 @@ use objdiff_core::{
     },
     config::path::platform_path,
     diff,
-    obj::{self, SectionKind, SymbolFlag},
+    obj::{self, SectionKind, SymbolFlag, SymbolKind},
 };
 use prost::Message;
 use rayon::iter::{IntoParallelRefIterator, ParallelIterator};
@@ -247,6 +247,7 @@ fn report_object(
                 || symbol.size == 0
                 || symbol.flags.contains(SymbolFlag::Hidden)
                 || symbol.flags.contains(SymbolFlag::Ignored)
+                || symbol.kind == SymbolKind::Section
             {
                 continue;
             }