Backport logGamma dragonfly fix (from ltsmaster impl)#64

kinke merged 2 commits intoldc-developers:ldcldc-developers/phobos:ldcfrom

dkgroot-ldc:backport_phobos_ltsmaster_logGamma_fixdkgroot-ldc/phobos:backport_phobos_ltsmaster_logGamma_fixCopy head branch name to clipboard