test case for dladdr()

Test case for dladdr(), to make sure it returns correct symbol in these cases:
 - addr is less than 'vfprintf'. Should returns another symbol.
 - addr is equals to 'vfprintf'. Should returns 'vfprintf' as the result.
 - addr is bigger than 'vfprintf', and also inside of it. Should returns 'vfprintf' as the result.

Reviewed-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Takuya ASADA <syuu@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>