RFR: JDK-8171167: Build fails in Mach 5 with "File name too long."

[Erik Joelsson]

Hello,

Please review this small fix, correcting a mistake in 
https://bugs.openjdk.java.net/browse/JDK-8170878. I generate a temporary 
file to store the file list to be included in each bundle, for each src 
root dir. The problem is that to make the file unique, I used the full 
path of the src root dir. In this patch, I cut off the part outside the 
TOPDIR of the workspace. That part will be the same for any src root 
anyway so cutting it will not affect uniqueness.

Bug: https://bugs.openjdk.java.net/browse/JDK-8171167

Webrev: http://cr.openjdk.java.net/~erikj/8171167/webrev.01/

/Erik