seedrng: use libbb functions

- Make extensive use of libbb.h functions, which simplify a lot of code
  and reduce binary size considerably.
- Use the already existing PID_FILE_PATH variable.

function                                             old     new   delta
seed_from_file_if_exists                             697     533    -164
.rodata                                           108665  108484    -181
seedrng_main                                        1463    1218    -245
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-590)           Total: -590 bytes
   text	   data	    bss	    dec	    hex	filename
 977035	   4227	   1848	 983110	  f0046	busybox_old
 976445	   4227	   1848	 982520	  efdf8	busybox_unstripped

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
1 file changed