Log Message:
Update libsoxr to 0.1.3.

Version 0.1.3 (2018-02-24)
  * SIMD enhancements: SSE, AVX, Neon.
  * Improve support for clang, ARM, and cross-compilation.
  * Provide env. var. override of runtime parameters.
  * Build fix re cmake variables AVCODEC_INCLUDE_DIRS & AVUTIL_INCLUDE_DIRS.
  * Build options WITH_SINGLE_PRECISION, WITH_DOUBLE_PRECISION & WITH_SIMD have
    been removed; replacement options are detailed in INSTALL, `Resampling
    engines'.