constantNumericValue() matched strtolower($name) with no namespace
resolution, so two invalid folds happened: `namespace N;
const PHP_INT_MAX = 5; PHP_INT_MAX + 1` folded to 9.22e18 where PHP
resolves the namespaced constant and yields 6, and a lowercase
`php_int_max` silently folded to the global value where PHP raises an
undefined-constant Error.
Resolve the fetched name the way parseConstFetch() does: a `use const`
alias resolves to its target, a fully qualified name is global, an
unqualified name inside a namespace participates in PHP's runtime
fallback (Namespace\NAME can be defined before the fetch executes) and
therefore never provably names the global, and the match is now
case-sensitive. Only a provable global PHP_INT_MAX/PHP_INT_MIN folds.
Alessio Giacobbe