sceFontStringRefersRenderCharacters had no test. The new one builds strings
from a text source and checks the cases that do not depend on bidirectional
text: an empty string gives no characters and a count of zero, a missing
count output or string gives a null result, no start character means the
first one, and a start or last character that lies before or after the
characters of the string, or a start after the last character, gives no
characters. Sub-ranges of a left-to-right run return the start character and
the number of characters from start to last.
Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
