use online drsyms for drheapstat for leak reporting

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on June 18, 2012 22:09:44_

xref issue #828 for heap usage callstacks which should probably remain
post-processed for app execution performance reasons.

for leaks we can do online symbolization and leak reporting.
that requires sharing the error reporting and suppressing logic in
report.c.

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=926_