Merge branch 'cwc' into 'master'

【修改内容】提交NX5的编译支持

See merge request chenweican/k-sdk!83

tools/board/config.linux.nx5

+CONFIG_ENV_CFLAGS   += \
+    -Os -Wall \
+    -g3 --coverage \
+    -D_PLATFORM_IS_LINUX_ \
+
+CONFIG_ENV_CFLAGS   += \
+    -DWITH_MQTT_DYN_BUF=1 \
+    -DWITH_MEM_STATS=0 \
+    -DWITH_MEM_STATS_PER_MODULE=0 \
+    -DWITH_MQTT_JSON_FLOW=1 \
+    -DWITH_MQTT_ZIP_TOPIC=1 \
+    -DWITH_MQTT_SUB_SHORTCUT=1 \
+    -DSDK_TEAM_TEST \
+	-D_GNU_SOURCE \
+	
+CONFIG_ENV_CFLAGS   += \
+    -DCONFIG_HTTP_AUTH_TIMEOUT=500 \
+    -DCONFIG_MID_HTTP_TIMEOUT=500 \
+    -DCONFIG_GUIDER_AUTH_TIMEOUT=500 \
+    -DCONFIG_MQTT_RX_MAXLEN=5000 \
+    -DCONFIG_MBEDTLS_DEBUG_LEVEL=0 \
+
+
+CONFIG_ENV_CFLAGS   += -rdynamic
+CONFIG_ENV_CFLAGS   += -Wno-unused -std=c99 
+
+CONFIG_ENV_LDFLAGS  += -lpthread -lrt
+
+OVERRIDE_CC = arm-kk-linux-gnueabihf-gcc
+OVERRIDE_AR = arm-kk-linux-gnueabihf-ar
+OVERRIDE_LD = arm-kk-linux-gnueabihf-ld
+CROSS_PREFIX = arm-kk-linux-gnueabihf-
+
+OVERRIDE_STRIP      := strip
+