www/axis2: Update to 1.7.5

Maintenance release that includes fixes for several issues, including a local
file inclusion vulnerability (AXIS2-5846).

Changes: http://axis.apache.org/axis2/java/core/release-notes/1.7.5.html

Approved by: garga (mentor)
MFH: 2017Q2
Differential Revision: https://reviews.freebsd.org/D10784