[llvm] [SPARC] Add TTI implementation for getPopcntSupport (PR #178843)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-aarch64-sve-vla` running on `linaro-g3-02` while building `llvm` at step 14 "test-suite".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/17/builds/14630

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 14 (test-suite) failure: test (failure)
...
size..init_array: 16 
size..interp: 27 
size..note.ABI-tag: 32 
size..plt: 992 
size..rela.dyn: 3168 
size..rela.plt: 1440 
size..rodata: 25620 
size..text: 707376 
**********
NOEXE: test-suite :: Fortran/gfortran/regression/gfortran-regression-execute-regression__f_c_string1_f90.test (5924 of 10355)
******************** TEST 'test-suite :: Fortran/gfortran/regression/gfortran-regression-execute-regression__f_c_string1_f90.test' FAILED ********************
Executable '/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/test/sandbox/build/Fortran/gfortran/regression/gfortran-regression-execute-regression__f_c_string1_f90' is missing
********************
NOEXE: test-suite :: Fortran/gfortran/regression/gfortran-regression-execute-regression__f_c_string2_f90.test (5925 of 10355)
******************** TEST 'test-suite :: Fortran/gfortran/regression/gfortran-regression-execute-regression__f_c_string2_f90.test' FAILED ********************
Executable '/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/test/sandbox/build/Fortran/gfortran/regression/gfortran-regression-execute-regression__f_c_string2_f90' is missing
********************
PASS: test-suite :: Fortran/gfortran/regression/gfortran-regression-execute-regression__eoshift_4_f90.test (5926 of 10355)
********** TEST 'test-suite :: Fortran/gfortran/regression/gfortran-regression-execute-regression__eoshift_4_f90.test' RESULTS **********
compile_time: 1.1866 
exec_time: 0.1420 
hash: "376a322cb5ee76c9c6c7e5fe3f27f129" 
link_time: 0.0000 
size: 1209664 
size..bss: 682832 
size..comment: 258 
size..data: 768 
size..data.rel.ro: 416 
size..dynamic: 496 
size..dynstr: 686 
size..dynsym: 1752 
size..eh_frame: 50536 
size..eh_frame_hdr: 12612 
size..fini: 20 
size..fini_array: 8 
size..gnu.hash: 28 
size..gnu.version: 146 
size..gnu.version_r: 96 
size..got: 240 
size..got.plt: 528 
size..init: 24 
size..init_array: 24 
size..interp: 27 
size..note.ABI-tag: 32 
size..plt: 1040 
size..rela.dyn: 2832 
size..rela.plt: 1512 
size..rodata: 29954 
size..text: 771696 

```

</details>

https://github.com/llvm/llvm-project/pull/178843