Squashed commit of various optimizations

Credits to OmniROM and the authors of each of these commits:

    bionic: call stdio cleanup on exit

    libc: krait: Re-factor high-performance memcpy for thumb2

    libm: krait: Fix build warning for e_pow.o

    Bionic/libm: Remove extra vmov from sin/cos.

    Bionic/libm: enable optimized math functions on more QCOM targets.

    libm: optimistic pow calling.

    libm: sqrt and sqrtf via ARM vsqrt instruction

    Bionic/libm: add assembly versions of sin/cos.

    Bionic/libm: Pow optimizations and bug fixes.

    Bionic/libm: Add precision-correct de-serialize sin/cos.

    Bionic/libm: Prefer branches and VFP ABI.

    Bionic/libm: fast neon pow() for small x,y.

Change-Id: Ic353045d77c89c1e3714b0a8a6e70b375485387a