Why do I get extra system calls when compiling code directly to an executable vs. compiling to an object file and then manually linking?

Question

I want to compile this C code with the GNU C Compiler on Ubuntu without linking any standard libraries, having only the following code execute.

static void exit(long long code)
  {asm inline
  ("movq $60,%%rax\n"
  "movq %[code],%%rdi\n"
  "syscall"
  :
  :[code]"rm"(code)
  :"rax"
  ,"rdi");}
static void write(long long fd,char *msg,long long len)
  {asm inline
  ("movq $0x1,%%rax\n"
  "movq %[fd],%%rdi\n"
  "movq %[msg],%%rsi\n"
  "movq %[len],%%rdx\n"
  "syscall"
  :
  :[fd]"rm"(fd)
  ,[msg]"rm"(msg)
  ,[len]"rm"(len)
  :"rax"
  ,"rdi"
  ,"rsi"
  ,"rdx");}
#define PRINT(msg) write(1,msg,sizeof(msg))
void _start()
  {PRINT("Hello World.\n");
  exit(0);}

I compiled with cc example.c -ffreestanding -nostartfiles -O3 -o example.

When I called the output file I saw a lot of extra system calls with strace that should not have been there:

1. brk
2. arch_prctl
3. access
4. mmap
5. arch_prctl
6. mprotect

I then compiled like this: cc example.c -c -O3 -o example.o; ld example.o -o example and it did not do the extra syscalls. It even made the filesize somewhat smaller.

The objdump -d of it was exactly the same. In the objdump -D I found some extra symbols (_DYNAMIC,__GNU_EH_FRAME_HDR,.interp) in the first case compared to the second, but still no sign of any extra syscalls in the code.

Do you know why I get the extra system calls with cc example.c -ffreestanding -nostartfiles -O3 -o example and not with cc example.c -c -O3 -o example.o; ld example.o -o example?