Our dlmalloc implementation currently calls abort() when it detects
that the heap is corrupted, or that an invalid pointer is passed to
one of its functions.
The only way to detect this is because abort() will force-fully
crash the current program with a magic fault address of '0xdeadbaad'.
However, this is not really well documented, and a frequent topic
on the android-ndk forum (among others).
This change makes our dlmalloc code dump a simple message to the
log just before the abort() call (and hence before the stack trace)
to better help identify the problem.
Change-Id: Iebf7eb7fe26463ecadfaca8f247d237edb441e3c
Simplify the code a little, removing un-necessary mutex locks/unlocks.
Provide slightly better diagnostic message in case of corruption.
Use snprintf/strlcat instead of sprintf/strcat
