Revert "epatch.eclass: drop 'estack.eclass' usage"

estack.eclass is needed for evar_push/evar_pop. The issue mentioned
in bug 662586 was fixed indenpendently in estack.eclass, so there is
no longer any need for the workaround (see comment #27 of that bug).

This reverts commit b21e386a06.

Signed-off-by: Ulrich Müller <ulm@gentoo.org>

eclass/epatch.eclass

@@ -19,6 +19,8 @@ case ${EAPI:-0} in
 		die "${ECLASS}: banned in EAPI=${EAPI}; use eapply* instead";;
 esac
 
+inherit estack
+
 # @VARIABLE: EPATCH_SOURCE
 # @DESCRIPTION:
 # Default directory to search for patches.
@@ -209,14 +211,13 @@ epatch() {
 		# Let people filter things dynamically
 		if [[ -n ${EPATCH_EXCLUDE}${EPATCH_USER_EXCLUDE} ]] ; then
 			# let people use globs in the exclude
-			local prev_noglob=$(shopt -p -o noglob)
-			set -o noglob
+			eshopts_push -o noglob
 
 			local ex
 			for ex in ${EPATCH_EXCLUDE} ; do
 				if [[ ${patchname} == ${ex} ]] ; then
 					einfo "  Skipping ${patchname} due to EPATCH_EXCLUDE ..."
-					${prev_noglob}
+					eshopts_pop
 					continue 2
 				fi
 			done
@@ -224,12 +225,12 @@ epatch() {
 			for ex in ${EPATCH_USER_EXCLUDE} ; do
 				if [[ ${patchname} == ${ex} ]] ; then
 					einfo "  Skipping ${patchname} due to EPATCH_USER_EXCLUDE ..."
-					${prev_noglob}
+					eshopts_pop
 					continue 2
 				fi
 			done
 
-			${prev_noglob}
+			eshopts_pop
 		fi
 
 		if [[ ${SINGLE_PATCH} == "yes" ]] ; then