examples: api: allow build with private libgcc

The examples/api is not configured with USE_PRIVATE_LIBGCC.  This makes
building examples/api break on certain boards that do not/cannot use the
public libgcc.

Nevertheless, this patch has to also touch the top-level Makefile to fix
this problem because the current top-level Makefile does not specify
libgcc as a prerequisite of examples/api, and explicitly builds
examples/api _before_ libgcc.

For testing this patch, I added the following to configs/seaboard.h and
ran demo.bin on a Seaboard.

+#define CONFIG_API
+#define CONFIG_SYS_MMC_MAX_DEVICE 2
+#define CONFIG_CMD_NET
+#define CONFIG_NET_MULTI

Signed-off-by: Che-Liang Chiou <clchiou@chromium.org>
Acked-by: Mike Frysinger <vapier@gentoo.org>