更新最新版不ffmpeg代码之后，在mingw下编译总是会莫名其妙出现一下的错误
../libavutil/libm.h:62: error: static declaration of 'lrint' follows non-static declaration
../libavutil/libm.h:69: error: static declaration of 'lrintf' follows non-static declaration
../libavutil/libm.h:76: error: static declaration of 'round' follows non-static declaration
../libavutil/libm.h:83: error: static declaration of 'roundf' follows non-static declaration
./libavutil/libm.h:90: error: static declaration of 'truncf' follows non-static declaration解决办法在config.h搜索lrint、lrintf、round、roundf等对于的字符
#define HAVE_LLRINT 1
#define HAVE_LLRINTF 1
#define HAVE_LRINT 1
#define HAVE_LRINTF 1
#define HAVE_ROUND 1
#define HAVE_ROUNDF 1