target: fix crash with jimtcl 0.78

target: fix crash with jimtcl 0.78

The jimtcl commit 41c5ff1809f5 ("jim.c: Fix Object leak in zlib
support") https://repo.or.cz/jimtcl.git/commit/41c5ff1809f5
makes Jim_SetResultFormatted() freeing the parameters that have
zero refcount.

OpenOCD commit 559d08c19ed8 ("jim tests: use installed") adds the
only code instance in OpenOCD that first passes a zero refcount
object to Jim_SetResultFormatted() and then frees it.
By switching jimtcl version to 0.78 or newer this causes a crash
of OpenOCD.
To trigger the crash in a telnet session, check that the current
target is running and type:
	[target current] arp_waitstate halted 1

Remove the call to Jim_FreeNewObj() after the call to
Jim_SetResultFormatted().

Change-Id: I5f5a8bca96a0e8466ff7b789fe578ea9785fa550
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/5453
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>