mtools_4.0.18.bb: Use create_wrapper() for mcopy

mcopy uses the IBM850 codepage from gconv. The default install location
for gconv will not match the actual install location since it can be
pulled from sstate. This patch overrides the default location when
running by adding GCONV_PATH to the environment for mcopy.

[YOCTO #7629]

(From OE-Core rev: ba3493c434ced719135082607e5f2e1d87559952)

Signed-off-by: Randy Witt <randy.e.witt@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/mtools/mtools_4.0.18.bb

@@ -45,3 +45,8 @@ do_install_prepend () {
     mkdir -p ${D}/${bindir}
     mkdir -p ${D}/${datadir}
 }
+
+do_install_append_class-native () {
+    create_wrapper ${D}${bindir}/mcopy \
+        GCONV_PATH=${libdir}/gconv
+}