Correct build rules for threads component.

Seem to have a cut-n-paste error, when compared to all other
components.

Author: petterreinholdtsen

src/Makefile

@@ -894,7 +894,7 @@ obj-$(CONFIG_PID) += pid.o
 pid-objs := hal/components/pid.o $(MATHSTUB)
 obj-$(CONFIG_AT_PID) += at_pid.o
 at_pid-objs := hal/components/at_pid.o $(MATHSTUB)
-obj-$(CONFIG_PID) += threads.o
+obj-$(CONFIG_THREADS) += threads.o
 threads-objs := hal/components/threads.o $(MATHSTUB)
 obj-$(CONFIG_SUPPLY) += supply.o
 supply-objs := hal/components/supply.o $(MATHSTUB)

src/Makefile.inc.in

@@ -193,6 +193,7 @@ CONFIG_AT_PID=m
 CONFIG_PID=m
 CONFIG_SUPPLY=m
 CONFIG_CLASSICLADDER_RT=m
+CONFIG_THREADS=m
 CONFIG_TIMEDELAY=m
 CONFIG_SIM_ENCODER=m
 CONFIG_WEIGHTED_SUM=m