Support floating point numbers in instruments CSV

When I generate Instruments data with the sample interval set to 40
microseconds instead of 1 ms and then export the data, I get Self values
that are sometimes floating point fractional numbers of ms.

Modify the regex to account for the potential of these numbers.

stackcollapse-instruments.pl

@@ -14,7 +14,7 @@
 <>;
 foreach (<>) {
 	chomp;
-	/\d+\.\d+ms[^,]+,(\d+),\s+,(\s*)(.+)/ or die;
+	/\d+\.\d+ms[^,]+,(\d+(?:\.\d*)?),\s+,(\s*)(.+)/ or die;
 	my $func = $3;
 	my $depth = length ($2);
 	$stack [$depth] = $3;