Returns the value associated with @key under @group_name as an
integer.
If @key cannot be found then 0 is returned and @error is set to
#G_KEY_FILE_ERROR_KEY_NOT_FOUND. Likewise, if the value associated
with @key cannot be interpreted as an integer, or is out of range
for a #gint, then 0 is returned
and @error is set to #G_KEY_FILE_ERROR_INVALID_VALUE.
Returns the value associated with @key under @group_name as an integer.
If @key cannot be found then 0 is returned and @error is set to #G_KEY_FILE_ERROR_KEY_NOT_FOUND. Likewise, if the value associated with @key cannot be interpreted as an integer, or is out of range for a #gint, then 0 is returned and @error is set to #G_KEY_FILE_ERROR_INVALID_VALUE.