Oct 26 (Reuters) - Computer hard drive maker Seagate Technology (STX.O) forecast second-quarter revenue below estimates on Thursday, a sign that demand stays weak for its data storage products amid a PC market slump. Seagate expects revenue for the current quarter to be $1.55 billion, plus or minus $150 million, the midpoint of which was below estimates of $1.61 billion, according to LSEG data. High borrowing costs and fears over the economic outlook have over the past year slammed demand for memory chips after a pandemic-driven boom. Demand also remains low in China, the market for nearly a third of...