fix sign compare warnings

Do explicit casts before comparing signed with unsigned.  The one in
log.c actually fixes another warning: in the expanded macro, there may
be a check "logLevel>=0", which is always true.

git-svn-id: https://svn.musicpd.org/mpd/trunk@7230 09075e82-0dd4-0310-85a5-a0d7c8717e4f

src/log.c

@@ -169,7 +169,7 @@ void setup_log_output(const int use_stdout)
 #define log_func(func,level,fp) \
 mpd_printf void func(const char *fmt, ...) \
 { \
-	if (logLevel >= level) { \
+	if ((int)logLevel >= level) {		\
 		va_list args; \
 		va_start(args, fmt); \
 		do_log(fp, fmt, args); \