Use maps::parse_filtered() for process symbolization

In general not all entries in /proc/[pid]/maps are of interest to us and
we perform some pre-filtering based on somewhat coarse grained criteria.
However, for one reason or another we didn't do that in the
symbolization logic, only when normalizing. Having failed to surface why
that is, exactly, let's switch over to using the filtered version
nonetheless, as none of our tests fail with the filtered version. Do so
should speed up things a bit and make follow-on changes easier to
digest.

Signed-off-by: Daniel Müller <deso@posteo.net>

src/symbolize/symbolizer.rs

@@ -898,7 +898,7 @@ impl Symbolizer {
         perf_map: bool,
         map_files: bool,
     ) -> Result<Vec<Symbolized>> {
-        let mut entry_iter = maps::parse(pid)?;
+        let mut entry_iter = maps::parse_filtered(pid)?;
         let entries = |_addr| entry_iter.next();
 
         let mut handler = SymbolizeHandler {