Can't build on Mac (Catalina)

[Taygair]

Hello
When I try to make build bsdiff or bspatch on Mac (Catalina) I got this error:

cc bspatch.c -o bspatch
Undefined symbols for architecture x86_64:
"_main", referenced from:
implicit entry/start for main executable
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [bspatch] Error 1

[drake127]

You need to define BSDIFF_EXECUTABLE and BSPATCH_EXECUTABLE macro to build the executable.