Fix head race condition introduced by optimizations. · libbitcoin/libbitcoin-database@cf55c3e

autoconf 2.72 is already installed and up-to-date. To reinstall 2.72, run: brew reinstall autoconf

libtool 2.4.7 is already installed and up-to-date. To reinstall 2.4.7, run: brew reinstall libtool

pkg-config 0.29.2_3 is already installed and up-to-date. To reinstall 0.29.2_3, run: brew reinstall pkg-config