elfutils: needs wchar

elfutils contains a call to wmempcpy, which is only available when the
toolchain has wchar support, so add the dependency.

Also display a comment if the toolchain dependencies are not met.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/elfutils/Config.in

@@ -1,3 +1,6 @@
+comment "elfutils requires a toolchain with LARGEFILE and WCHAR support"
+	depends on !BR2_LARGEFILE || !BR2_USE_WCHAR
+
 config BR2_PACKAGE_ELFUTILS
 	bool "elfutils"
 	select BR2_PACKAGE_ARGP_STANDALONE if \
@@ -6,6 +9,7 @@ config BR2_PACKAGE_ELFUTILS
 	       BR2_TOOLCHAIN_EXTERNAL_UCLIBC
 	select BR2_PACKAGE_GETTEXT if BR2_NEEDS_GETTEXT
 	depends on BR2_LARGEFILE
+	depends on BR2_USE_WCHAR
 	help
 	  Libraries/utilities to handle ELF objects (drop in
 	  replacement for libelf).