Update cov-diff to handle new gcov, and remove timestamps

The new gcov sometimes emits *s if there is a line containing
multiple basic blocks, and some are not executed.  (The gcov
documentation says something weird about this point, so I'm trying
to interpret it into the compilerese that I'm familiar with.)
That's bug 26101.

Also, when we're looking for unique variations in our coverage, we
would like cov-diff to suppress timestamps on the diffs.  That's bug
26102.

Both of these are bugfixes on 0.2.5.1-alpha when the cov-diff script
was introduced.

My apologies for the perl.

changes/bug26101_26102

@@ -0,0 +1,5 @@
+  o Minor bugfixes (test coverage tools):
+    - Update our "cov-diff" script to handle output from the latest
+      version of gcov, and to remove extraneous timestamp information
+      from its output. Fixes bugs 26101 and 26102; bugfix on
+      0.2.5.1-alpha.

scripts/test/cov-diff

@@ -10,12 +10,12 @@ DIRB="$2"
 for B in $DIRB/*; do
   A=$DIRA/`basename $B`
   if [ -f $A ]; then
-      perl -pe 's/^\s*\!*\d+:/        1:/; s/^([^:]+:)[\d\s]+:/$1/; s/^ *-:(Runs|Programs):.*//;' "$A" > "$A.tmp"
+      perl -pe 's/^\s*\!*\d+(\*?):/        1$1:/; s/^([^:]+:)[\d\s]+:/$1/; s/^ *-:(Runs|Programs):.*//;' "$A" > "$A.tmp"
   else
       cat /dev/null > "$A.tmp"
   fi
-  perl -pe 's/^\s*\!*\d+:/        1:/; s/^([^:]+:)[\d\s]+:/$1/; s/^ *-:(Runs|Programs):.*//;' "$B" > "$B.tmp"
-  diff -u "$A.tmp" "$B.tmp"
+  perl -pe 's/^\s*\!*\d+(\*?):/        1$1:/; s/^([^:]+:)[\d\s]+:/$1/; s/^ *-:(Runs|Programs):.*//;' "$B" > "$B.tmp"
+  diff -u "$A.tmp" "$B.tmp" |perl -pe 's/^((?:\+\+\+|---)(?:.*tmp))\s+.*/$1/;'
   rm "$A.tmp" "$B.tmp"
 done