When building with gcc 4.4.7, this error occurs (due to a change in behaviour in later versions of gcc, which let you redefine typedefs without an error as long as you don't change the definition):

pulsecore/packet.c:43: error: redefinition of typedef ‘pa_packet’
pulsecore/packet.h:26: note: previous declaration of ‘pa_packet’ was here

Fix is to remove the typedef from packet.c and just define the struct:

struct pa_packet {
    PA_REFCNT_DECLARE;
    enum { PA_PACKET_APPENDED, PA_PACKET_DYNAMIC } type;
    size_t length;
    uint8_t *data;
    union {
        uint8_t appended[MAX_APPENDED_SIZE];
    } per_type;
};