package/dash: fix build failure due to wchar

Since commit [1] package dash requires wchar so let's depend on it to
fix build failure. Doing so makes default non-busybox shell dash to
depend on wchar. This is too restrictive since this way wchar becomes
mandatory, so let's switch default non-busybox shell to bash.

[1]:
https://git.kernel.org/pub/scm/utils/dash/dash.git/commit/?id=c0674f487c7aec2a3bdf6795cea7e60c9530c360

Fixes:
https://autobuild.buildroot.org/results/e9108ebd9fb8c471add1c5a7f581757175fa5f15/

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/dash/Config.in

@@ -2,6 +2,7 @@ config BR2_PACKAGE_DASH
 	bool "dash"
 	depends on BR2_USE_MMU # fork()
 	depends on BR2_PACKAGE_BUSYBOX_SHOW_OTHERS
+	depends on BR2_USE_WCHAR
 	help
 	  DASH is a POSIX-compliant implementation of /bin/sh that
 	  aims to be as small as possible. It does this without
@@ -10,3 +11,8 @@ config BR2_PACKAGE_DASH
 	  for most tasks.
 
 	  http://gondor.apana.org.au/~herbert/dash
+
+comment "dash needs a toolchain w/ wchar"
+	depends on BR2_USE_MMU
+	depends on BR2_PACKAGE_BUSYBOX_SHOW_OTHERS
+	depends on !BR2_USE_WCHAR

system/Config.in

@@ -399,7 +399,7 @@ config BR2_TARGET_GENERIC_ROOT_PASSWD
 
 choice
 	bool "/bin/sh"
-	default BR2_SYSTEM_BIN_SH_DASH if !BR2_PACKAGE_BUSYBOX
+	default BR2_SYSTEM_BIN_SH_BASH if !BR2_PACKAGE_BUSYBOX
 	help
 	  Select which shell will provide /bin/sh.
 
@@ -418,6 +418,7 @@ config BR2_SYSTEM_BIN_SH_DASH
 	bool "dash"
 	depends on BR2_USE_MMU # dash
 	depends on BR2_PACKAGE_BUSYBOX_SHOW_OTHERS
+	depends on BR2_USE_WCHAR # dash
 	select BR2_PACKAGE_DASH
 
 config BR2_SYSTEM_BIN_SH_MKSH