include/stdio.h:373: error: no previous prototype for 'getc'

错误提示：
$ make install
CC /usr/local/lib/libavdevice.a
In file included from d:/ffmpeg/libavformat/avformat.h:55,
from d:/ffmpeg/libavdevice/alldevices.c:22:
D:/MingW/include/stdio.h:372: error: no previous prototype for 'getc'
D:/MingW/include/stdio.h:379: error: no previous prototype for 'putc'
D:/MingW/include/stdio.h:386: error: no previous prototype for 'getchar'
D:/MingW/include/stdio.h:393: error: no previous prototype for 'putchar'
D:/MingW/include/stdio.h:606: error: no previous prototype for 'vsnwprintf'

去掉configure 文件文件里的

该标签存在两次都去掉
check_cflags -Werror=missing-prototypes

原因是

ffmpeg 的 configure 文件，3.8号更新了 添加了 -Werror=missing-prototypes 这个编译选择项
Error on missing function prototypes with gcc

This makes it an error to not have a prototype in scope for
a function with external linkage. The flag is only enabled
for gcc due to -Werror=type not working with all compilers.