Basically, this is purely a debian/rules specific issue for armel. There is an entirely separate issue for lpia.
The problem I believe is that build-arch conditionally bypasses building for long double on some architectures, per:
# build only on architectures where double != long-double
gcc -o test_long_long-double debian/test_long_long-double.c
if ! ./test_long_long-double; then \
However, binary-arch: has no conditional check for including the result and so assumes long-double has been built :).
I think this is a very simple fix, and I expect to have a patch for this later today, once I test building both for armel and x86. This bug report is hence I hope simply so I can attach the debdiff for my change and request sponsoring it when I am done.
I was delayed with a fs crash. This should be in today.