4.6.1.4 Config Option
The -mconfig option can be used to have the compiler
program default values for those configuration bits that have not been specified in the
code using the config pragma. The alternate form of this option is
-mdefault-config-bits.
The default operation is to not program unspecified bits, and this can be
made explicit using the -mno-config option (or its equivalent,
-mno-default-config-bits).
