Slight optimization when copying OUString.
Slight optimization when copying OUString.

Change-Id: If934e18c0fd68d89d838ca9717aa2e4616bc3b6a

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