fix out of tree builds

--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -7,7 +7,7 @@
 	Client.h \
 	fam.c++
 
-libfam_la_LDFLAGS = -export-symbols fam.sym
+libfam_la_LDFLAGS = -export-symbols $(srcdir)/fam.sym
 libfam_la_LIBADD = -lstdc++
 
 EXTRA_DIST = fam.sym