ooxml: fix import of custDash shape line attribute
ooxml: fix import of custDash shape line attribute

A LineProperties object can contain some preset dash defined by the
shape style and some custom dash defined by the shape properties. In
that case, the custom dash must be used.

The existing code only used the custom dash if no preset dash was
present.

Change-Id: I6254d95184312360e8782dba7329d5ec2f5441fa

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core