utils: add/replace string equality macros It's more tidy and less error prone, since we use strcasecmp == 0 a lot. We replace strcmp == 0 by streq, strcasecmp == 0 by istreq, uStrCasePrefix by istreq_prefix and uDupString by strdup_safe. Signed-off-by: Ran Benita <ran234@gmail.com>