Bugs (and fixes) in pathalias

[code 101]

Re (1), USG and index/rindex/strchr/strrchr:  if you define ATTSV in
config.h, def.h will define index and rindex for you.

Re (2), MYMALLOC commentary:  Geoff oversimplifies.  It's true that
myfree() is a no-op, but observe that mymalloc() uses a buffered sbrk()
scheme.  I did a lot of profiling, against every version of malloc I
could find and discovered that mymalloc() wins on time *and* space.
It's easy to see why it wins on time.  For space, I found that almost
all of the free()-ing comes after almost all of the malloc()-ing, thus
very little space is re-used, so you never win back the space
overhead.

Re (3), core dump if you don't use mymalloc():  thank you, I'll look at
this right away.

	Peter