testcase/kernel: Add test case for difftime()
testcase/kernel: Add test case for difftime()

Adds test case for api difftime().

Testcase Result:
	TASH>>kernel_tc
	########## Kernel TC Start ##########

	[tc_libc_timer_clock] PASS

	[tc_libc_timer_clock_calendar2utc] PASS

	[tc_libc_timer_clock_daysbeforemonth] PASS

	[tc_libc_timer_clock_isleapyear] PASS

	[tc_libc_timer_difftime] PASS

	[tc_libc_timer_gmtime] PASS

	[tc_libc_timer_gmtime_r] PASS

	[tc_libc_timer_localtime] PASS

	[tc_libc_timer_localtime_r] PASS

	[tc_libc_timer_mktime] PASS

	[tc_libc_timer_strftime] PASS

	[tc_libc_timer_strptime] PASS

	[tc_libc_timer_time] PASS

	########## Kernel TC End [PASS : 13, FAIL : 0] ##########

Signed-off-by: Lokesh B V <a10c1c2561c872cd1fd5899c4340d5ec87a91507@partner.samsung.com>

Samsung/TizenRT,Samsung/TizenRT,chanijjani/TizenRT,Samsung/TizenRT,pillip8282/TizenRT,jeongarmy/TizenRT,junmin-kim/TizenRT,pillip8282/TizenRT,jeongarmy/TizenRT,sunghan-chang/TizenRT,chanijjani/TizenRT,pillip8282/TizenRT,an4967/TizenRT,an4967/TizenRT,JeonginKim/TizenRT,JeonginKim/TizenRT,chanijjani/TizenRT,jeongarmy/TizenRT,Samsung/TizenRT,pillip8282/TizenRT,HONGCHAEHEE/TizenRT,davidfather/TizenRT,sunghan-chang/TizenRT,jsdosa/TizenRT,jeongchanKim/TizenRT,sunghan-chang/TizenRT,chanijjani/TizenRT,davidfather/TizenRT,pillip8282/TizenRT,chanijjani/TizenRT,jeongchanKim/TizenRT,chanijjani/TizenRT,an4967/TizenRT,sunghan-chang/TizenRT,junmin-kim/TizenRT,jeongchanKim/TizenRT,chanijjani/TizenRT,HONGCHAEHEE/TizenRT,an4967/TizenRT,an4967/TizenRT,JeonginKim/TizenRT,HONGCHAEHEE/TizenRT,jsdosa/TizenRT,junmin-kim/TizenRT,HONGCHAEHEE/TizenRT,davidfather/TizenRT,HONGCHAEHEE/TizenRT,JeonginKim/TizenRT,pillip8282/TizenRT,junmin-kim/TizenRT,JeonginKim/TizenRT,davidfather/TizenRT,jsdosa/TizenRT,davidfather/TizenRT,jeongchanKim/TizenRT,jeongchanKim/TizenRT,Samsung/TizenRT,jsdosa/TizenRT,junmin-kim/TizenRT,davidfather/TizenRT,davidfather/TizenRT,jeongarmy/TizenRT,pillip8282/TizenRT,jeongarmy/TizenRT,jeongchanKim/TizenRT,junmin-kim/TizenRT,HONGCHAEHEE/TizenRT,jsdosa/TizenRT,jsdosa/TizenRT,jeongarmy/TizenRT,sunghan-chang/TizenRT,jsdosa/TizenRT,an4967/TizenRT,sunghan-chang/TizenRT,JeonginKim/TizenRT,jeongchanKim/TizenRT,jeongarmy/TizenRT,Samsung/TizenRT,Samsung/TizenRT,an4967/TizenRT,junmin-kim/TizenRT,sunghan-chang/TizenRT