S-Record lexer: correctly count the characters of an invalid short line

If the line only consisted of 3 digits (e.g. S12), then highlighting of
the third one (first digit of the "count" field) was dependent on the
content of the subsequent line. Now this digit is always highlighted as
valid "byte count", independent on its value, if there is no further
digit behind.

The function return value can be negative now.

0 files changed, 0 insertions, 0 deletions