代码补丁

##1.打补丁
###1.1.文件差异补丁
格式： diff -u basefile newfile > out.patch
例子：diff -u libavfilter/vf_drawtext_old.c libavfilter/vf_drawtext.c > /root/mscore/src/patch/drawtext_force_boxw_equl_textw.patch

###1.2.ffmpeg补丁
git diff > /root/mscore/src/patch/drawtext_force_boxw_equl_textw.patch

##2.ffmpeg应用补丁
git apply drawtext_force_boxw_equl_textw.patch