Compile the regular expression regex into a form that is suitable for subsequent regexec searches

Property definitions

core $ NativeRegex :: regcomp
	# Compile the regular expression `regex` into a form that is suitable for subsequent `regexec` searches
	fun regcomp(regex: CString, cflags: Int): Int `{
		return regcomp(self, regex, cflags);
	`}
lib/core/re.nit:44,2--47,3