apertium-init doesn't make corpus dir

```
fran@matxine:/tmp/apertium-pus$ ./autogen.sh
make
configure.ac:4: installing './install-sh'
configure.ac:4: installing './missing'
Makefile.am: installing './INSTALL'
checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /bin/mkdir -p
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking whether make supports nested variables... yes
checking whether ln -s works... yes
checking for gawk... (cached) gawk
checking for pkg-config... /usr/bin/pkg-config
checking pkg-config is at least version 0.9.0... yes
checking for APERTIUM... yes
checking for LTTOOLBOX... yes
checking for cg-comp... /usr/bin/cg-comp
checking that generated files are newer than configure... done
configure: creating ./config.status
config.status: creating Makefile
config.status: creating apertium-pus.pc
fran@matxine:/tmp/apertium-pus$ make
apertium-validate-dictionary apertium-pus.pus.dix
lt-comp lr apertium-pus.pus.dix pus.automorf.bin apertium-pus.pus.acx
final@inconditional 4 11
main@standard 16 22
lt-print pus.automorf.bin | gzip -9 -c -n > pus.automorf.att.gz
test -d .deps || mkdir .deps
touch .deps/.d
apertium-validate-dictionary apertium-pus.pus.dix
lt-comp rl apertium-pus.pus.dix pus.autogen.bin apertium-pus.pus.acx
final@inconditional 4 11
main@standard 16 22
lt-print pus.autogen.bin | gzip -9 -c -n > pus.autogen.att.gz
lt-comp lr apertium-pus.post-pus.dix pus.autopgen.bin
main@standard 5 8
make: *** No rule to make target 'corpus/pus.tagged', needed by 'pus.prob'. Stop.
```

The failure occurs while building the `pus.prob` target, which expects `corpus/pus.tagged`; start by tracing the `apertium-init` entry point that creates the corpus directory and reproduce the shown `make` command. Done means initialization creates the directory before the target is built and the build no longer stops with “No rule to make target”.

Written by the indexing model from the issue text.