ffmpeg compile with GDB debug info

1. In config.mak:

     CFLAGS=   -std=c99 -pthread -g3 -Wdeclaration-after-statement -Wall -Wdisabled-optimization -Wpointer-arith -Wredundant-decls -Wwrite-strings -Wtype-limits -Wundef -Wmissing-prototypes -Wno-pointer-to-int-cast -Wstrict-prototypes -Wempty-body -Wno-parentheses -Wno-switch -Wno-format-zero-length -Wno-pointer-sign  -fno-math-errno -fno-signed-zeros -fno-tree-vectorize -Werror=format-security -Werror=implicit-function-declaration -Werror=missing-prototypes -Werror=return-type -Werror=vla -Wformat -fdiagnostics-color=auto -Wno-maybe-uninitialized 2../configure --enable-shared --disable-yasm --enable-debug=3--disable-optimizations --disable-stripping --prefix=/usr/local/ffmpeg

3. make , make install

3. gdb ./ffmpeg

gdb>     r -i src -y dst