Log Message:
devel/rgbds: Update to 0.3.8

Changes:

rgbasm and rgblink
    Report correct filename and line number of symbols in error messages.
    Fix long-standing issue of ambiguity in constant parsing.
    Fix behaviour of parser regarding newlines and \.

rgbfix
    Fix regression on calculation of ROM checksum.

Other
    Documentation updates and cleanups.
    Some new tests.
    Re-enabled OS X build CI job.