[llvm] [AArch64][SVE] Remove isSVECC() in favour of changing the calling convention (PR #152742)

[Sander de Smalen via llvm-commits]

================
@@ -1546,40 +1482,33 @@ define tailcc void @f15(double %d, <vscale x 4 x i32> %vs, [9 x i64], i32 %i) {
 ; CHECK-LABEL: f15:
 ; CHECK:       .seh_proc f15
 ; CHECK-NEXT:  // %bb.0:
-; CHECK-NEXT:    addvl sp, sp, #-1
----------------
sdesmalen-arm wrote:

The LangRef says that the calling convention requires the prototype of all callees to exactly match the prototype of the function definition. So I guess adding `tailcall` on this function is not correct.

https://github.com/llvm/llvm-project/pull/152742