logcfg: Don't generate macros for nameless levels
logcfg: Don't generate macros for nameless levels

The generated `logcfg.h` file contains some extraneous macros.  For
example:

    #define DFLT_LOG_DEBUG(...) IGNORE(__VA_ARGS__)
    #define DFLT_LOG_INFO(...) MODLOG_INFO(0, __VA_ARGS__)
    #define DFLT_LOG_WARN(...) MODLOG_WARN(0, __VA_ARGS__)
    #define DFLT_LOG_ERROR(...) MODLOG_ERROR(0, __VA_ARGS__)
    #define DFLT_LOG_CRITICAL(...) MODLOG_CRITICAL(0, __VA_ARGS__)
    #define DFLT_LOG_(...) MODLOG_(0, __VA_ARGS__)
    #define DFLT_LOG_(...) MODLOG_(0, __VA_ARGS__)
    #define DFLT_LOG_(...) MODLOG_(0, __VA_ARGS__)
    #define DFLT_LOG_(...) MODLOG_(0, __VA_ARGS__)
    #define DFLT_LOG_(...) MODLOG_(0, __VA_ARGS__)
    #define DFLT_LOG_(...) MODLOG_(0, __VA_ARGS__)
    #define DFLT_LOG_(...) MODLOG_(0, __VA_ARGS__)
    #define DFLT_LOG_(...) MODLOG_(0, __VA_ARGS__)
    #define DFLT_LOG_(...) MODLOG_(0, __VA_ARGS__)
    #define DFLT_LOG_(...) MODLOG_(0, __VA_ARGS__)
    #define DFLT_LOG_DISABLED(...) MODLOG_DISABLED(0, __VA_ARGS__)

The generated code should look like this:

    #define DFLT_LOG_DEBUG(...) IGNORE(__VA_ARGS__)
    #define DFLT_LOG_INFO(...) MODLOG_INFO(0, __VA_ARGS__)
    #define DFLT_LOG_WARN(...) MODLOG_WARN(0, __VA_ARGS__)
    #define DFLT_LOG_ERROR(...) MODLOG_ERROR(0, __VA_ARGS__)
    #define DFLT_LOG_CRITICAL(...) MODLOG_CRITICAL(0, __VA_ARGS__)
    #define DFLT_LOG_DISABLED(...) MODLOG_DISABLED(0, __VA_ARGS__)

The extraneous macros are generated because log levels 5 through 14 do
not have names (between CRITICAL and DISABLED).

This commit removes the extraneous macros from the generated code.

apache/incubator-mynewt-newt,apache/incubator-mynewt-newt