Description:kernelspace musl code

Team:OTHERS
Feature or Bugfix:Feature
Binary Source:NA
PrivateCode(Yes/No):No

Change-Id: I99874a7c570b7d22b4a3d34840260eb48ea3ffa1
Reviewed-on: http://mgit-tm.rnd.huawei.com/10276995Reviewed-by: Nshenwei 00579521 <denny.shenwei@huawei.com>
Tested-by: Npublic jenkins <public_jenkins@notesmail.huawei.com>

from https://github.com/ARM-software/optimized-routines,
commit 04884bd04eac4b251da4026900010ea7d8850edc

In expf TOINT_INTRINSICS is kept, but is unused, it would require support
for __builtin_round and __builtin_lround as single instruction.

code size change: +94 bytes.
benchmark on x86_64 before, after, speedup:

-Os:
  expf rthruput:   9.19 ns/call  8.11 ns/call 1.13x
   expf latency:  34.19 ns/call 18.77 ns/call 1.82x
 exp2f rthruput:   5.59 ns/call  6.52 ns/call 0.86x
  exp2f latency:  17.93 ns/call 16.70 ns/call 1.07x
-O3:
  expf rthruput:   9.12 ns/call  4.92 ns/call 1.85x
   expf latency:  34.44 ns/call 18.99 ns/call 1.81x
 exp2f rthruput:   5.58 ns/call  4.49 ns/call 1.24x
  exp2f latency:  17.95 ns/call 16.94 ns/call 1.06x