Add in output samplerate

[armandobelardo]

Addresses #26

[armandobelardo]

@chrisstaite I was wondering if you've seen this issue before, I was trying to build locally to test out the change but I'm running into some cpp build issues

libtool: link: sed 's|^|_|' < ../include/libmp3lame.sym > .libs/libmp3lame-symbols.expsym
libtool: link: gcc -dynamiclib  -o .libs/libmp3lame.0.dylib  .libs/VbrTag.o .libs/bitstream.o .libs/encoder.o .libs/fft.o .libs/gain_analysis.o .libs/id3tag.o .libs/lame.o .libs/newmdct.o .libs/presets.o .libs/psymodel.o .libs/quantize.o .libs/quantize_pvt.o .libs/reservoir.o .libs/set_get.o .libs/tables.o .libs/takehiro.o .libs/util.o .libs/vbrquantize.o .libs/version.o .libs/mpglib_interface.o   -Wl,-force_load,../mpglib/.libs/libmpgdecoder.a  -lm  -O3 -arch x86_64 -mmacosx-version-min=10.6 -arch x86_64 -mmacosx-version-min=10.6   -install_name  /Users/armandobelardo/Git/oss/forks/lameenc/build/lame/src/lame/lib/libmp3lame.0.dylib -compatibility_version 1 -current_version 1.0 -Wl,-exported_symbols_list,.libs/libmp3lame-symbols.expsym
ld: Undefined symbols:
  _init_xrpow_core_sse, referenced from:
      _init_xrpow_core_init in quantize.o
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[6]: *** [libmp3lame.la] Error 1
make[5]: *** [all-recursive] Error 1
make[4]: *** [all-recursive] Error 1
make[3]: *** [all] Error 2
make[2]: *** [lame/src/lame-stamp/lame-build] Error 2
make[1]: *** [CMakeFiles/lame.dir/all] Error 2
make: *** [all] Error 2

UPDATE: I brute forced this a bit and forced the CMake file to build for my arch and it then built in full
I was able to test this local version in my application and confirmed it does indeed address #26

if (APPLE)
    set(BUILT_FILE "lameenc-1.0.0-cp34-cp34m-macosx_10_6_intel.whl")
    set(HOST "")
    # if ("${CMAKE_OSX_ARCHITECTURES}" STREQUAL "x86_64" OR "${CMAKE_OSX_ARCHITECTURES}" STREQUAL "")
    #   set(ARCH_FLAGS "-arch x86_64")
    # endif ()
    # if ("${CMAKE_OSX_ARCHITECTURES}" STREQUAL "arm64")
    set(ARCH_FLAGS "${ARCH_FLAGS} -arch arm64")
    set(HOST_PLATFORM "_PYTHON_HOST_PLATFORM=macosx-11.0-arm64")
    set(HOST "--host=aarch64")
    # endif ()
    set(LAME_FLAGS "${ARCH_FLAGS} -mmacosx-version-min=10.6")
    set(LAME_CONFIGURE "<SOURCE_DIR>/configure" "CFLAGS=${LAME_FLAGS}" "LDFLAGS=${LAME_FLAGS}"
        "--prefix=<BINARY_DIR>" "${HOST}"
        "--enable-expopt" "--enable-nasm" "--disable-frontend" "--disable-analyzer-hooks"
        "--disable-debug" "--disable-dependency-tracking")
    set(LAME_INSTALL $(MAKE) install)
elseif (WIN32)

[chrisstaite]

Looks good, just a couple of touch ups please.