Branding signage for WPP, the largest global advertising and public relations agency at their offices in London, Britain, July 17, 2019. REUTERS/Toby Melville/File Photo Acquire Licensing Rights LONDON, Oct 26 (Reuters) – WPP (WPP.L), the world's largest ad group, cut its outlook for the second quarter in a row on Thursday, saying it now expected like-for-like growth this year to be 0.5-1.0%, as big tech client continued in rein in marketing spend. "Our top-line performance in Q3 was below our expectations and continued to be impacted by the cautious spending trends we saw in Q2, particularly across technology clients with…