Makefile: fix typo

Commit 95695388 introduced new util/virthreadjob.c/h files but the
makefile has type that breaks rpm build.
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

src/Makefile.am

@@ -160,7 +160,7 @@ UTIL_SOURCES =							\
 		util/virsysinfo.c util/virsysinfo.h		\
 		util/virsystemd.c util/virsystemd.h		\
 		util/virthread.c util/virthread.h		\
-		util/virthreadjob.c utils/virthreadjob.h	\
+		util/virthreadjob.c util/virthreadjob.h		\
 		util/virthreadpool.c util/virthreadpool.h	\
 		util/virtime.h util/virtime.c			\
 		util/virtpm.h util/virtpm.c			\