Bug#865671: scotch hides build failures

[Aaron M. Ucko]

Source: scotch
Version: 6.0.4.dfsg1-2
Followup-For: Bug #865671

Specifically, debian/rules contains several shell loops that run
without either set -e or explicit error handling.  As such, Hurd
builds running afoul of #881200 attempt to build all four variants of
the library, encounter compilation and upstream installation errors
for each of them, and don't actually fail until debian/rules tries to
rename gmap.1 to scotch_gmap.1 (presumably to avoid a file conflict).

-- 
Aaron M. Ucko, KB1CJC (amu at alum.mit.edu, ucko at debian.org)
http://www.mit.edu/~amu/ | http://stuff.mit.edu/cgi/finger/?amu@monk.mit.edu