Use extended symbolization markup on Fuchsia (#559)

{{{reset:begin/end}}} pair will allow symbolization to be performed on
the whole stack rather than individual frames.

src/print.rs

@@ -83,7 +83,8 @@ impl<'a, 'b> BacktraceFmt<'a, 'b> {
  /// This is currently a no-op but is added for future compatibility with
  /// backtrace formats.
  pub fn finish(&mut self) -> fmt::Result {
- // Currently a no-op-- including this hook to allow for future additions.
+ #[cfg(target_os = "fuchsia")]
+ fuchsia::finish_context(self.fmt)?;
  Ok(())
  }
 

src/print/fuchsia.rs

@@ -425,7 +425,7 @@ impl DsoPrinter<'_, '_> {
 
 /// This function prints the Fuchsia symbolizer markup for all information contained in a DSO.
 pub fn print_dso_context(out: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
- out.write_str("{{{reset}}}\n")?;
+ out.write_str("{{{reset:begin}}}\n")?;
  let mut visitor = DsoPrinter {
  writer: out,
  module_count: 0,
@@ -434,3 +434,8 @@ pub fn print_dso_context(out: &mut core::fmt::Formatter<'_>) -> core::fmt::Resul
  for_each_dso(&mut visitor);
  visitor.error
 }
+
+/// This function prints the Fuchsia symbolizer markup to end the backtrace.
+pub fn finish_context(out: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+ out.write_str("{{{reset:end}}}\n")
+}