FFmpeg iOS build script

This is a shell script to build FFmpeg libraries for iOS and tvOS apps.

Tested with:

Requirements

Use build-ffmpeg-tvos.sh for tvOS.

To build everything:
```
  ./build-ffmpeg.sh
```
To build arm64 libraries:
```
  ./build-ffmpeg.sh arm64
```
To build fat libraries for armv7 and x86_64 (64-bit simulator):
```
  ./build-ffmpeg.sh armv7 x86_64
```
To build fat libraries from separately built thin libraries:
```
  ./build-ffmpeg.sh lipo
```

You should link your app with

Name		Name	Last commit message	Last commit date
Latest commit History 14 Commits
FFmpeg-iOS		FFmpeg-iOS
fat-x264		fat-x264
ffmpeg-2.8.5		ffmpeg-2.8.5
scratch		scratch
thin		thin
Build FFmpeg libraries and libx264 for iOS.docx		Build FFmpeg libraries and libx264 for iOS.docx
Partition_List.cpp		Partition_List.cpp
README.md		README.md
VS2013编译FFmpeg.docx		VS2013编译FFmpeg.docx
aki_352x288.h264		aki_352x288.h264
bridge-close_qcif.h264		bridge-close_qcif.h264
build-ffmpeg-tvos.sh		build-ffmpeg-tvos.sh
build-ffmpeg.sh		build-ffmpeg.sh
ds_480x272.yuv		ds_480x272.yuv
ffmpeg_video_encoder.cpp		ffmpeg_video_encoder.cpp
fix_pts.cpp		fix_pts.cpp
my_ffmpeg.cpp		my_ffmpeg.cpp
simplest_ffmpeg_video_encoder.cpp		simplest_ffmpeg_video_encoder.cpp
simplest_ffmpeg_video_encoder_pure.cpp		simplest_ffmpeg_video_encoder_pure.cpp