Merge "Replace FOURCC macro with constexpr"

namespace android {

#define FOURCC(c1, c2, c3, c4) \

    ((c1) << 24 | (c2) << 16 | (c3) << 8 | (c4))

constexpr int FOURCC(unsigned char c1, unsigned char c2, unsigned char c3, unsigned char c4) {

    return ((c1) << 24 | (c2) << 16 | (c3) << 8 | (c4));

}

template <size_t N>

constexpr int32_t FOURCC(const char (&s) [N]) {

    static_assert(N == 5, "fourcc: wrong length");

    return

            (unsigned char) s[0] << 24 |

            (unsigned char) s[1] << 16 |

            (unsigned char) s[2] << 8 |

            (unsigned char) s[3] << 0;

}

uint16_t U16_AT(const uint8_t *ptr);

uint32_t U32_AT(const uint8_t *ptr);