format: Use json_object_object_get_ex() instead of deprecated json_object_object_get()

format: Use json_object_object_get_ex() instead of deprecated json_object_object_get()

pulse/format.c: In function 'pa_format_info_get_prop_type':
pulse/format.c:252:5: warning: implicit declaration of function 'is_error' [-Wimplicit-function-declaration]
pulse/format.c:287:13: warning: 'json_object_object_get' is deprecated (declared at /usr/local/include/json-c/json_object.h:290) [-Wdeprecated-declarations]
pulse/format.c:293:13: warning: 'json_object_object_get' is deprecated (declared at /usr/local/include/json-c/json_object.h:290) [-Wdeprecated-declarations]
pulse/format.c: In function 'pa_format_info_get_prop_int_range':
pulse/format.c:364:5: warning: 'json_object_object_get' is deprecated (declared at /usr/local/include/json-c/json_object.h:290) [-Wdeprecated-declarations]
pulse/format.c:369:5: warning: 'json_object_object_get' is deprecated (declared at /usr/local/include/json-c/json_object.h:290) [-Wdeprecated-declarations]
pulse/format.c: In function 'pa_format_info_prop_compatible':
pulse/format.c:676:9: warning: 'json_object_object_get' is deprecated (declared at /usr/local/include/json-c/json_object.h:290) [-Wdeprecated-declarations]
pulse/format.c:680:9: warning: 'json_object_object_get' is deprecated (declared at /usr/local/include/json-c/json_object.h:290) [-Wdeprecated-declarations]

json-c 0.10 (released 20120530) added json_object_object_get_ex()
json-c 0.12 (released 20140410) deprecated json_object_object_get()

PulseAudio depends on json 0.9 or json-c 0.11, drop support for json 0.9
in a subsequent patch and require json-c 0.11 (this will also avoids confusion
which json package is needed due to the upstream rename)

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>