Created attachment 402736 [details]
chrony-2.0 has a hand-written configure script, and it makes heavy use of "echo -n". The echo builtin in dash just outputs a literal "-n" for this, instead of suppressing the \n, and in this case causes a huge mess that gcc isn't happy with (see attached build log if you're curious). I have "eselect sh" more or less evenly split between machines, and only the ones using dash fail here.
I've seen the related discussion in bug 523874 which seems to share the same root cause, and it seems like dash is being (unhelpfully) posixly-correct.
Adding 2 chars to a file in chrony's source seems by far the easiest fix and is probably what the original author intended, so here:
--- chrony-2.0/configure.orig 2015-04-27 11:58:19.000000000 +0100
+++ chrony-2.0/configure 2015-05-06 04:32:22.066289557 +0100
@@ -1,4 +1,4 @@
# chronyd/chronyc - Programs for keeping computer clocks accurate.
Fixed without revision bump.