Full compiler log at e.g.
http://buildbot.askmonty.org/buildbot/builders/sol10-64/builds/3308/steps/compile/logs/stdio

cd /export/home/buildbot/maria-slave/solaris10-x86/build/mariadb-10.1.2/wsrep && /usr/sfw/bin/gcc -DHAVE_RWLOCK_T -DHAVE_CONFIG_H -Wall -mtune=i386 -D__sun -m64 -mtune=athlon64 -DWITH_INNODB_DISALLOW_WRITES -Wall -O2 -g -DDBUG_OFF -I/export/home/buildbot/maria-slave/solaris10-x86/build/mariadb-10.1.2/include -fPIC -o CMakeFiles/wsrep.dir/wsrep_gtid.c.o -c /export/home/buildbot/maria-slave/solaris10-x86/build/mariadb-10.1.2/wsrep/wsrep_gtid.c
In file included from /export/home/buildbot/maria-slave/solaris10-x86/build/mariadb-10.1.2/wsrep/wsrep_api.h:51,
from /export/home/buildbot/maria-slave/solaris10-x86/build/mariadb-10.1.2/wsrep/wsrep_gtid.c:24:
/usr/include/stdbool.h:42:2: #error "Use of <stdbool.h> is valid only in a c99 compilation environment."
gmake[2]: Leaving directory `/export/home/buildbot/maria-slave/solaris10-x86/build/mariadb-10.1.2'
gmake[2]: *** [wsrep/CMakeFiles/wsrep.dir/wsrep_gtid.c.o] Error 1
gmake[1]: *** [wsrep/CMakeFiles/wsrep.dir/all] Error 2
gmake[1]: *** Waiting for unfinished jobs....