hg: code-tools/jtreg: Set EXE_SUFFIX in WSL mode

[jonathan.gibbons at oracle.com]

Changeset: 1ec40d0dd0b5
Author:    jjg
Date:      2019-01-16 11:13 -0800
URL:       http://hg.openjdk.java.net/code-tools/jtreg/rev/1ec40d0dd0b5

Set EXE_SUFFIX in WSL mode

! src/share/classes/com/sun/javatest/regtest/exec/ShellAction.java