Bug 1654158 - Improve symbols list diffs in diffoscope tasks. r=froydnj

This helps a little with the diffs from bug 1654123.

Differential Revision: https://phabricator.services.mozilla.com/D84289

taskcluster/docker/diffoscope/Dockerfile

@@ -25,5 +25,6 @@ RUN apt-get install \
     locale-gen
 
 COPY get_and_diffoscope /builds/worker/bin/get_and_diffoscope
+COPY readelf /builds/worker/bin/readelf
 
 RUN chown -R worker:worker /builds/worker/bin && chmod 755 /builds/worker/bin/*

taskcluster/docker/diffoscope/get_and_diffoscope

@@ -7,6 +7,10 @@ cd /builds/worker
 
 mkdir a b
 
+# /builds/worker/bin contains wrapper binaries to divert what diffoscope
+# needs to use, so it needs to appear first.
+export PATH=/builds/worker/bin:$PATH
+
 # Until https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=879010 is
 # implemented, it's better to first manually extract the data.
 # Plus dmg files are not supported yet.
@@ -26,7 +30,6 @@ case "$ORIG_URL" in
 	for tool in lipo otool; do
 		ln -s $MOZ_FETCHES_DIR/cctools/bin/x86_64-apple-darwin*-$tool bin/$tool
 	done
-	export PATH=$PATH:/builds/worker/bin
 	curl -L "$ORIG_URL" > a.dmg
 	curl -L "$NEW_URL" > b.dmg
 	for i in a b; do

taskcluster/docker/diffoscope/readelf

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+case "$1 $2" in
+"--wide --symbols")
+    # When called with --wide --symbols, we remove the first column (which
+    # is essentially a line number that is not very useful), and then sort,
+    # which will order symbols by address, making a diff more useful.
+    /usr/bin/readelf "$@" | awk -F: '{print $2}' | sort
+    ;;
+*)
+    exec /usr/bin/readelf "$@"
+    ;;
+esac