examples/timer: fix the compilation error caused by CONFIG_DISABLE_SIGNALS

The commit 'add support for CONFIG_DISABLE_SIGNALS' led to:

undefined reference to `sigaction'

Signed-off-by: v-tangmeng <[email protected]>

Author: TangMeng12

examples/timer/Kconfig

@@ -6,7 +6,7 @@
 config EXAMPLES_TIMER
 	tristate "Timer example"
 	default n
-	depends on TIMER
+	depends on TIMER && !DISABLE_SIGNALS
 	---help---
 		Enable the timer example