tools: Fix rcompile to work under other LANG settings

This is because the only portable way to detect whether something
is a function is to use the output of 'type'. That output is
translated (the -t option is not portable).

Fixes #1380
Closes #1382
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
test: Fixes to make tests set LANG=C before running

Lots of stuff requires parsing output from the host, including
log lines, and diagnostic messages from rpmbuild

Closes #1383
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>