epunt-cxx.eclass: Switch to using patches from elt-patches pkg

Switch to using the patches provided through the app-portage/elt-patches
package, like libtool.eclass. Since epunt-cxx is no longer implicit
eutils API but a dedicated eclass, we do not have to worry about
the extra dependency.

eclass/epunt-cxx.eclass

@@ -14,19 +14,7 @@ if [[ -z ${_EPUNT_CXX_ECLASS} ]]; then
 # eutils for eqawarn
 inherit eutils
 
-# If an overlay has eclass overrides, but doesn't actually override the
-# libtool.eclass, we'll have ECLASSDIR pointing to the active overlay's
-# eclass/ dir, but libtool.eclass is still in the main Gentoo tree.  So
-# add a check to locate the ELT-patches/ regardless of what's going on.
-# Note: Duplicated in libtool.eclass.
-_EUTILS_ECLASSDIR_LOCAL=${BASH_SOURCE[0]%/*}
-eutils_elt_patch_dir() {
-	local d="${ECLASSDIR}/ELT-patches"
-	if [[ ! -d ${d} ]] ; then
-		d="${_EUTILS_ECLASSDIR_LOCAL}/ELT-patches"
-	fi
-	echo "${d}"
-}
+DEPEND=">=app-portage/elt-patches-20170317"
 
 # @FUNCTION: epunt_cxx
 # @USAGE: [dir to scan]
@@ -41,7 +29,7 @@ epunt_cxx() {
 	ebegin "Removing useless C++ checks"
 	local f p any_found
 	while IFS= read -r -d '' f; do
-		for p in "$(eutils_elt_patch_dir)"/nocxx/*.patch ; do
+		for p in "${EPREFIX}/usr/share/elt-patches"/nocxx/*.patch ; do
 			if patch --no-backup-if-mismatch -p1 "${f}" "${p}" >/dev/null ; then
 				any_found=1
 				break