tdf#42374, improve perf by fixing bug in pdfi::HashedStyle::hashCode()
tdf#42374, improve perf by fixing bug in pdfi::HashedStyle::hashCode()

which was rendering it largely useless for hashing purposes

Change-Id: Ie94457ea0a6e53fd9ceed9461656e2d3b0840d58

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