am -i, git-svn: use "git var GIT_PAGER"

Use the new "git var GIT_PAGER" command to ask what pager to use.

Without this change, the core.pager configuration is ignored by
these commands.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-am.sh

@@ -649,7 +649,10 @@ do
 		[eE]*) git_editor "$dotest/final-commit"
 		       action=again ;;
 		[vV]*) action=again
-		       LESS=-S ${PAGER:-less} "$dotest/patch" ;;
+		       : ${GIT_PAGER=$(git var GIT_PAGER)}
+		       : ${LESS=-FRSX}
+		       export LESS
+		       $GIT_PAGER "$dotest/patch" ;;
 		*)     action=again ;;
 		esac
 	    done