tools/tools-common.h: introduce CGROUP_LOG_CONT level for logging

tools/tools-common.h: introduce CGROUP_LOG_CONT level for logging

There are cases, where we might want to print a very long/multiline log
message to the user. We could call the cgroup_log(), multiple times
to fit the log message, but the downside is that every time the
cgroup_log() called, the log level is prefixed to the message, hence
introducing loglevel char string in the mid of the log message.

Introduce a new logging level, CGROUP_LOG_CONT and cgroup_cont() macro,
that will continue printing the log message, when loglevel is set to
other than default log level. The above code can be rewritten as:

Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>
TJH: Fix typo in commit message
(cherry picked from commit db2039f6ad75988e0aad3f5306d5d8c02aa4b040)