ApfGenerator - addAdd/Mul/Div use unsigned immediates

See apf interpreter implementation:
  https://source.corp.google.com/h/android/platform/superproject/+/main:hardware/google/apf/apf_interpreter.c;l=219 & 222 & 225

which use 'imm' not 'signed_imm'.

See also:
  http://cs/h/android/platform/superproject/+/main:hardware/google/apf/apf.h?l=146

where only LI, LDDW, STDW mention 'signed' or 'simm'.
(and SH by mentioning -5 directly)

addAdd - seems to only be called with non-negative values from
         non-test code, while the tests do use negatives,
         they only do so with 32-bit values at which point it
         no longer matters
(there is likely a bug this fixes in Bpf2Apf.java,
 but I don't think we use it)

addMul - only called from test with 2

addDiv - only called from test with 0 or 2

Bug: 298842151
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Id641774b01bbbc9f4bbcbb0d232faabb745634b2
1 file changed