build idea

[Zack Weinberg]

While working on my new testsuite stuff I noticed that several things
(particularly running just-built programs, but installation would
benefit too) would get simpler if the extra libraries and the dynamic
linker were moved to top level of the build tree.  IOW, instead of
doing

$(objpfx)libfoo.so: ...

you would have

$(common-objpfx)libfoo.so: ...

This is a win because you no longer have to know which directory a
library lives in to link with it.

Obviously this is something for the long term, but I wanted to know
what people thought of it.

zw