Fix build errors

Very small modifications allowing me to build showtime on debian sid.

Here is the build output before modification:
```
In file included from /home/pinchal/showtime/src/db/db_support.c:23:0:
/home/pinchal/showtime/src/db/db_support.c: In function ‘db_open’:
/home/pinchal/showtime/src/showtime.h:124:43: error: ‘page_count’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
 #define TRACE(level, subsys, fmt...) trace(0, level, subsys, fmt)
                                           ^
/home/pinchal/showtime/src/db/db_support.c:359:7: note: ‘page_count’ was declared here
   int page_count;
       ^
In file included from /home/pinchal/showtime/src/db/db_support.c:23:0:
/home/pinchal/showtime/src/showtime.h:124:43: error: ‘freelist_count’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
 #define TRACE(level, subsys, fmt...) trace(0, level, subsys, fmt)
                                           ^
/home/pinchal/showtime/src/db/db_support.c:358:7: note: ‘freelist_count’ was declared here
   int freelist_count;
       ^
cc1: all warnings being treated as errors
```