Converting the runtime-state mutexes to spinlocks

Runtime-state was using mutexes to protect some variables, whose updates/accesses are
very quick (ie. not involving IOs or compilcated calculations). The runtime-state objects
can be accessed concurrently by multiple threads and using mutexes for those short
critical sections can become a bottleneck. This patch replaces the mutexes with spinlocks.

Change-Id: Iba880ebda1f3d48c93cc73bae38669ff93ab2e28
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/5619
Reviewed-by: Daniel Hecht <dhecht@cloudera.com>
Tested-by: jenkins