compare_tests: Improve non-unique tests report

If the results include several configurations (schedule of
variations), do not report summary lines as duplicates.  Indeed with
several configurations, it's likely that the results contain the same

   # of expected passes            XXXXX

The patch just keeps lines starting with test state prefix to avoid
this problem.

contrib/ChangeLog:

	* compare_tests: Improve non-unique tests report when testing
	several configurations.

contrib/compare_tests

@@ -126,10 +126,18 @@ fi
 sort -t ':' $skip1 "$now" > "$now_s"
 sort -t ':' $skip1 "$before" > "$before_s"
 
-# Report non-unique test names, but print the two lists only if they
-# are different.
-sed '/^$/d' "$now_s"    | uniq -cd > "$now_u"
-sed '/^$/d' "$before_s" | uniq -cd > "$before_u"
+# Report non-unique test names and print the diff between the two
+# lists if they are different.
+#
+# If the results include several configurations (schedule of
+# variations), we report duplicates several times with different
+# target/tool prefixes because at this stage we do not know if the
+# target and/or tool prefix was inserted.
+# If we used the input files (so generally several times the same
+# results in one section per target), we would incorreclty detect
+# duplicates (as many as targets)
+grep -E '^(PASS|XPASS|FAIL|XFAIL|UNRESOLVED|UNSUPPORTED|UNTESTED|ERROR):' "$now_s"    | uniq -cd > "$now_u"
+grep -E '^(PASS|XPASS|FAIL|XFAIL|UNRESOLVED|UNSUPPORTED|UNTESTED|ERROR):' "$before_s" | uniq -cd > "$before_u"
 
 same_uniq=" now"
 cmp -s "$before_u" "$now_u" && same_uniq=""
@@ -142,8 +150,8 @@ if [ -s "$now_u" ]; then
 fi
 
 if [ -s "$before_u" -a "x$same_uniq" != "x" ]; then
-    echo "Non-unique test names before: (Eeek!)"
-    cat "$before_u"
+    echo "Changes to non-unique test names:"
+    diff -u "$before_u" "$now_u" | grep -E '^[-\\+] '
     echo
     exit_status=1
 fi