RFR: 8151600: Syntax for -Xlog complicates shell scripts

[Robbin Ehn]

Hi all,

The current syntax for -Xlog uses '*' for wildcard matching of tags.
In shell scripts where * is unintended expanded causes problems.
This patch adds the possibility to use trailing '+' instead.

E.g.
"-Xlog:gc+" is thus equivalent to "-Xlog:gc*"

Tested with modified gtest test.

Webrev: http://cr.openjdk.java.net/~rehn/8151600/hotspot.01/webrev/
Bug: https://bugs.openjdk.java.net/browse/JDK-8151600

Thanks!

/Robbin