Unify GREEDY_REALLOC and GREEDY_REALLOC_T

greedy_realloc() and greedy_realloc0() now store the allocated
size as the count, not bytes.

Replace GREEDY_REALLOC uses with GREEDY_REALLOC_T everywhere,
and then rename GREEDY_REALLOC_T to GREEDY_REALLOC. It is just
too error-prone to have two slightly different macros which do the
same thing.
test-dhcp-client: unref lease objects to make valgrind happy

Also unref client objects in test code, and initalize logging,
to DEBUG by default.
journal: cleanup up error handling in update_catalog()

- Negative/positive errno mixup caused duplicates not to be detected properly.
  Now we get a warning about some duplicate entries in our own catalogs...
- Errors in update_catalog would be ignored, but they should not be.
journal: properly detect language specified in line

... it turns out that the duplicates in our own catalog were not real
duplicates, but translations.
core: Make sure a stamp file exists for all Persistent=true timers

If a persistent timer has no stamp file yet, it behaves just like a normal
timer until it runs for the first time. If the system is always shut down
while the timer is supposed to run, a stamp file is never created and
Peristent=true has no effect.

This patch fixes this by creating a stamp file with the current time
when the timer is first started.