Fix compile warning: variable "c" was declared but never referenced, when RT_USING_CONSOLE is disable.
[BSP] Port to NuMicro M051 Series support for Nuvoton corp.
    1. adapt to M052xDN/xDE, M054xDN/xDE, M058xDN/xDE, M0516/xDN/xDE.
    2. support heap memory management.
Port to gcc and fix keil project
Merge pull request #384 from bright-pan/master

[BSP] Port to NuMicro M051 Series support for Nuvoton corp and fix compile warning