Add smtp client example

examples/smtp-client/Makefile

@@ -0,0 +1,20 @@
+PROG ?= example
+CFLAGS ?= -W -Wall -Wextra -O2 $(EXTRA_CFLAGS)
+SSL ?= MBEDTLS
+
+ifeq "$(SSL)" "MBEDTLS"
+CFLAGS += -DMG_ENABLE_MBEDTLS=1 -lmbedtls -lmbedcrypto -lmbedx509 -L$(MBEDTLS)/lib -I$(MBEDTLS)/include
+endif
+
+ifeq "$(SSL)" "OPENSSL"
+CFLAGS += -DMG_ENABLE_OPENSSL=1 -lssl -lcrypto -L$(OPENSSL)/lib -I$(OPENSSL)/include
+endif
+
+all: $(PROG)
+	$(RUN) ./$(PROG) $(ARGS)
+
+$(PROG): main.c
+	$(CC) ../../mongoose.c -I../.. $(CFLAGS) -o $(PROG) main.c
+
+clean:
+	rm -rf $(PROG) _CL* *.o *.dSYM *.gcov *.gcno *.gcda *.obj *.exe *.ilk *.pdb mbedtls