sh: enable CONFIG_USE_PRIVATE_LIBGCC by default

Now this feature works.  Let's turn it on by default so we do not
depend on specific tool-chains.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>

arch/sh/Kconfig

@@ -124,6 +124,9 @@ config SYS_CPU
 	default "sh3" if CPU_SH3
 	default "sh4" if CPU_SH4
 
+config USE_PRIVATE_LIBGCC
+	default y
+
 source "board/alphaproject/ap_sh4a_4a/Kconfig"
 source "board/espt/Kconfig"
 source "board/mpr2/Kconfig"