We are mostly likely not running as root, so this call will fail. As we are
supposed to check its return value as it's declared with
warn_unused_result, the current way of using it is wrong, so this commit just
removes the call.
Be more library friendly, by not aborting in library errors.
spice_common now includes a proper log handler that will abort by
default when reaching a warning.
SPICE_ABORT_LEVEL can be changed to modify run-time abort level.
SPICE_DEBUG_LEVEL can be changed to be more verbose. By default, only
log level more importants than WARNING.
Only memory-related functions are allowed to abort(), since they are
not recoverable errors in the library.
Add a backtrace printing function copied from xserver os/backtrace.c
that uses gstack, and if that isn't found then glibc's backtrace.
Used in ASSERT, tested on F15.
