export only required symbols, do not export internal symbols from the library

Hopefully I collected the list of symbols to expot correctly.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

Makefile.am

@@ -30,7 +30,8 @@ lib_libiscsi_la_SOURCES = \
 SONAME=$(firstword $(subst ., ,$(VERSION)))
 SOREL=$(shell printf "%d%02d%02d" $(subst ., ,$(VERSION)))
 lib_libiscsi_la_LDFLAGS = \
-	-version-info $(SONAME):$(SOREL):0 -bindir $(bindir) -no-undefined
+	-version-info $(SONAME):$(SOREL):0 -bindir $(bindir) -no-undefined \
+	-export-symbols lib/libiscsi.syms
 
 # libiscsi utilities