runtime/mercury_string.h:
As above. Valid code points in the ranges [1D800, 1DFFF] and
[10D800, 10DFFF] were treated like invalid surrogates because the
high bits were masked away.
tests/hard_coded/Mmakefile:
tests/hard_coded/char_not_surrogate.exp:
tests/hard_coded/char_not_surrogate.m:
tests/hard_coded/string_not_surrogate.exp:
tests/hard_coded/string_not_surrogate.m:
Add test cases.
