Merge topic 'math-expr-overflow'

2423db545f math: Avoid signed integer overflow on negation
d140e01447 cmExprParserHelper: Factor unary negation operation body out of the parser

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Merge-request: !11767