Add optional vscale prefix to loopinfo test

[pchintalapudi]

Fix #49325

[giordano]

$ make -C test/llvmpasses
make: Entering directory '/snx11273/home/ri-mgiordano/repo/julia/test/llvmpasses'
PATH=/snx11273/home/ri-mgiordano/repo/julia/usr/bin:/snx11273/home/ri-mgiordano/repo/julia/usr/tools:$PATH \
LD_LIBRARY_PATH=/snx11273/home/ri-mgiordano/repo/julia/usr/lib:$LD_LIBRARY_PATH \
/snx11273/home/ri-mgiordano/repo/julia/usr/tools/lit/lit.py -v "/snx11273/home/ri-mgiordano/repo/julia/test/llvmpasses/."
-- Testing: 35 tests, 35 workers --
UNSUPPORTED: Julia :: fmf.jl (1 of 35)
PASS: Julia :: alloc-opt-unsized.ll (2 of 35)
PASS: Julia :: propagate-addrspace.ll (3 of 35)
PASS: Julia :: remove-addrspaces.ll (4 of 35)
PASS: Julia :: float16.ll (5 of 35)
PASS: Julia :: returnstwicegc.ll (6 of 35)
PASS: Julia :: propagate-addrspace-non-zero.ll (7 of 35)
PASS: Julia :: lower-handlers-addrspaces.ll (8 of 35)
PASS: Julia :: muladd.ll (9 of 35)
PASS: Julia :: lower-handlers.ll (10 of 35)
PASS: Julia :: cpu-features.ll (11 of 35)
PASS: Julia :: final-lower-gc-addrspaces.ll (12 of 35)
PASS: Julia :: simdloop.ll (13 of 35)
PASS: Julia :: julia-licm.ll (14 of 35)
PASS: Julia :: refinements.ll (15 of 35)
PASS: Julia :: multiversioning-annotate-only.ll (16 of 35)
PASS: Julia :: final-lower-gc.ll (17 of 35)
PASS: Julia :: late-lower-gc.ll (18 of 35)
PASS: Julia :: late-lower-gc-addrspaces.ll (19 of 35)
PASS: Julia :: multiversioning-clone-only.ll (20 of 35)
PASS: Julia :: gcroots.ll (21 of 35)
PASS: Julia :: alloc-opt-gcframe-addrspaces.jl (22 of 35)
PASS: Julia :: alloc-opt-pass.jl (23 of 35)
PASS: Julia :: alloc-opt-gcframe.jl (24 of 35)
PASS: Julia :: alloc-opt-pipeline.jl (25 of 35)
PASS: Julia :: noinline.jl (26 of 35)
PASS: Julia :: fastmath.jl (27 of 35)
PASS: Julia :: llvmcall.jl (28 of 35)
PASS: Julia :: aliasscopes.jl (29 of 35)
PASS: Julia :: pipeline-o2-allocs.jl (30 of 35)
PASS: Julia :: loopinfo.jl (31 of 35)
PASS: Julia :: pipeline-o0.jl (32 of 35)
PASS: Julia :: pipeline-o2-broadcast.jl (33 of 35)
PASS: Julia :: pipeline-o2.jl (34 of 35)
PASS: Julia :: safepoint_stress.jl (35 of 35)

Testing Time: 185.24s
  Unsupported:  1
  Passed     : 34
make: Leaving directory '/snx11273/home/ri-mgiordano/repo/julia/test/llvmpasses'

Thanks!