xterm: enable for ARC external toolchain

With the latest prebuilt ARC toolchain this package is building
without any errors.

Signed-off-by: Evgeniy Didin <didin@synopsys.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: arc-buildroot@synopsys.com
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/xterm/Config.in

@@ -2,8 +2,6 @@ config BR2_PACKAGE_XTERM
 	bool "xterm"
 	depends on BR2_PACKAGE_XORG7
 	depends on BR2_USE_MMU # fork()
-	# ARC toolchain issue
-	depends on !BR2_TOOLCHAIN_EXTERNAL_SYNOPSYS_ARC
 	select BR2_PACKAGE_NCURSES
 	select BR2_PACKAGE_XLIB_LIBXAW
 	help