I'll start with the output
Code:
make rebuild
MAKECMDGOALS=rebuild
make -f main.mak rebuild
make[1]: Entering directory '~/alu'
PRJ_SRC_FILES = 'test.c alu_bit.c alu_main.c alu_math.c alu_mem.c alu_vec.c'
rm -f *.AppImage *.exe *.so *.dll *.o *.obj
cc -fPIC -shared -Wall -Wextra -I cloned/fbstdc/include  -o test.o -c test.c
make[1]: Leaving directory '~/alu'
fatal: not in a git directory
In file included from test.c:1:
alu.h:12:10: fatal error: allstdint.h: No such file or directory
   12 | #include <allstdint.h>
      |          ^~~~~~~~~~~~~
compilation terminated.
make[1]: *** [main.mak:98: test.o] Error 1
make: *** [1st.mak:6: rebuild] Error 2
Compilation failed.
I've checked and the files were certainly downloaded and saved to the right place, I'm guessing I'm using the -I flag wrong maybe? If you need more just tell me what you're looking for and I'll post it