Plus various minor build tweaks.

ported a version of the patch at https://bugzilla.gnome.org/show_bug.cgi?id=656531 adjusted for libreoffice

centralise cut/paste coding designed to explicitly load i18n and
i18npool libraries if UNO is not bootstrapped. Instead fallback to
the process service manager, and require this to be initialized,
even for small tools.

if < 1 GB do not auto-enable ccache
if < 5 GB warn about debug/symbol build