Cannot compile, using ffmpeg from sources

Hello, I'm using Ubuntu 18.04, did a clean install in a virtual machine. I downloaded libvpx from sources, compiled and installed without any problems.
Then I downloaded ffmpeg source (from git, from git clone https://git.ffmpeg.org/ffmpeg.git ffmpeg), and compiled it (passing --enable-libvpx to it), make compiled without any issues, and did a make install.

When I try to make the 0_hello_world.c, make gives me the following error:
(you can check the output with a better looking text at https://pastebin.com/wPKY99ue )

mkdir build
gcc -g -Wall -o build/hello_world -lavformat -lavcodec -lswscale -lavutil -lz 0_hello_world.c
&& ./build/hello_world small_bunny_1080p_60fps.mp4`
0_hello_world.c: In function ‘main’:
0_hello_world.c:35:3: warning: ‘av_register_all’ is deprecated [-Wdeprecated-declarations]
av_register_all();
^~~~~~~~~~~~~~~
In file included from 0_hello_world.c:15:0:
/usr/local/include/libavformat/avformat.h:2033:6: note: declared here
void av_register_all(void);
^~~~~~~~~~~~~~~
/tmp/ccbsfyh8.o: In function 'av_make_error_string':
/usr/local/include/libavutil/error.h:111: undefined reference to 'av_strerror'
/tmp/ccbsfyh8.o: In function 'main':
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:35: undefined reference to 'av_register_all'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:40: undefined reference to 'avformat_alloc_context'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:54: undefined reference to 'avformat_open_input'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:73: undefined reference to 'avformat_find_stream_info'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:103: undefined reference to 'avcodec_find_decoder'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:125: undefined reference to 'avcodec_alloc_context3'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:134: undefined reference to 'avcodec_parameters_to_context'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:142: undefined reference to 'avcodec_open2'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:149: undefined reference to 'av_frame_alloc'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:156: undefined reference to 'av_packet_alloc'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:180: undefined reference to 'av_packet_unref'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:168: undefined reference to 'av_read_frame'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:185: undefined reference to 'avformat_close_input'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:186: undefined reference to 'avformat_free_context'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:187: undefined reference to 'av_packet_free'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:188: undefined reference to 'av_frame_free'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:189: undefined reference to 'avcodec_free_context'
/tmp/ccbsfyh8.o: In function 'decode_packet':
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:207: undefined reference to 'avcodec_send_packet'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:218: undefined reference to 'avcodec_receive_frame'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:230: undefined reference to 'av_get_picture_type_char'
/home/xultz/libav/ffmpeg-libav-tutorial/0_hello_world.c:242: undefined reference to 'av_frame_unref'
collect2: error: ld returned 1 exit status
Makefile:4: recipe for target 'hello_world' failed
make: *** [hello_world] Error 1

I took a look at pkg-config outputs from --libs and --cflags for some libs (lib libavformat, libavutil, etc) and I changed the gcc line on the Makefile to the following, but I couldn't see any changes on the make output:
gcc -g -Wall -I/usr/local/include -o build/hello_world -L/usr/local/lib -lavformat -lavcodec -lswscale -lavutil -lz -lvpx -lm -lswresample -pthread 0_hello_world.c

What else can I do in order to compile the code?

Thank you in advance for any help!

Start by reproducing the failure with Makefile and 0_hello_world.c on the reported Ubuntu setup, then compare the Makefile gcc command with the shown pkg-config flags. Done means the hello_world target compiles and runs against the locally installed FFmpeg libraries.