Add shared library version of libcli_main

ports/nacl-spawn/Makefile

Index: ports/nacl-spawn/Makefile
diff --git a/ports/nacl-spawn/Makefile b/ports/nacl-spawn/Makefile
index 024563a2b2bd3376a2555860430fa808f4275dd9..6afcd691ff44bfc275e3f0d44b29187f4c4bab74 100644
--- a/ports/nacl-spawn/Makefile
+++ b/ports/nacl-spawn/Makefile
@@ -20,6 +20,9 @@ libcli_main.a: cli_main.o nacl_startup_untar.o
 	rm -f $@
 	$(NACLAR) rcs $@ $^
 
+libcli_main.so: cli_main.o nacl_startup_untar.o
+	$(NACLCXX) $(LDFLAGS) -shared $^ -o $@
+
 cli_main.o: cli_main.c
 	$(NACLCC) $(CFLAGS) -c $< -o $@
 
@@ -44,9 +47,9 @@ test: $(TEST_EXES) $(TEST_BINARIES)
 	./test/run_test.sh
 
 test/elf_reader: elf_reader.cc
-	$(NACLCXX) -DDEFINE_ELF_READER_MAIN $< -o $@
+	$(NACLCXX) $(LDFLAGS) $(CXXFLAGS) -DDEFINE_ELF_READER_MAIN $< -o $@
 test/library_dependencies: elf_reader.o path_util.o library_dependencies.cc
-	$(NACLCXX) -DDEFINE_LIBRARY_DEPENDENCIES_MAIN $^ -o $@
+	$(NACLCXX) $(LDFLAGS) $(CXXFLAGS) -DDEFINE_LIBRARY_DEPENDENCIES_MAIN $^ -o $@
 
 # We use -nostdlib not to have libc.so in their dependencies.
 test/test_exe: test/test_exe.c test/libtest1.so test/libtest2.so