Concerning compilation warning in string_search.h

[targos]

On Windows with MSVC, the implementation of StringSearch<Char>::BoyerMooreHorspoolSearch emits a concerning warning.

Code:

node/src/string_search.h

Lines 459 to 461 in fd02dac

	const size_t pattern_length = pattern_.length();
	int* char_occurrences = bad_char_shift_table_;
	int64_t badness = -pattern_length;

The emitted warning is C4146: unary minus operator applied to unsigned type, result still unsigned

This looks like it introduces a bug in the function, at least on Windows, because badness is never going to be a negative number.