The error does not matter because it is post building the libcrypto.a and the libssl.a. The error appears when applications for SSL are build which we do not need. The error happens because the Nios does not support shared libs.
If you want to compile without error make following lines a comment in
openssl.mk file:
$(OPENSSL_DIR)/apps/openssl: $(OPENSSL_DIR)/Makefile
$(MAKE1) CC=$(TARGET_CC) -C $(OPENSSL_DIR) all
# Work around openssl build bug to link libssl.a with libcrypto.a.
# -rm $(OPENSSL_DIR)/libssl.a.*.*.*
# $(MAKE1) CC=$(TARGET_CC) -C $(OPENSSL_DIR) do_linux-shared