expose symbols beginning with xornsch_

Index: xorn/src/storage/Makefile.in
--- xorn/src/storage/Makefile.in.orig
+++ xorn/src/storage/Makefile.in
@@ -427,7 +427,7 @@ libxornstorage_la_SOURCES = \
 	selection.cc \
 	validate.cc
 
-libxornstorage_la_LDFLAGS = -export-symbols-regex '^xorn_'
+libxornstorage_la_LDFLAGS = -export-symbols-regex '^xorn(sch)?_'
 all: all-am
 
 .SUFFIXES:
