Merge "Replace loop by __builtin_ctz"

int AudioMixer::getTrackName()

{

    uint32_t names = mTrackNames;

    uint32_t mask = 1;

    int n = 0;

    while (names & mask) {

        mask <<= 1;

        n++;

    }

    if (mask) {

    uint32_t names = ~mTrackNames;

    if (names != 0) {

        int n = __builtin_ctz(names);

        ALOGV("add track (%d)", n);

        mTrackNames |= mask;

        mTrackNames |= 1 << n;

        return TRACK0 + n;

    }

    return -1;