If someone is going to backport these packages, they may have an
interest in using versioned directories. These will most likely
attempt to set directories on the build command line, thus it is
most natural to insert a suggestion about this option there.
Files that are distributed as packages should always assume that all
the other libraries it depends on is as packages too, in the system
directories, so there is no need to have a RUNPATH embedded in them.
When using LTO, the linker calls back to the compiler to figure out
where a certain symbol is defined. However, in many versions there
is apparently a bug that is triggered if a template in inlined in
both a used library and in the main program, but with different
versions of the compiler. The Boost exception class is particular
prone for this.
Thus, we disable the -lto from the development builds by default;
if anyone wants to test of the behaviour of their own compiler, they
must now explicitly turn on this flag.
