Align arm64 data section as requested

Currently, the data section alignment request is ignored unless
it is 8. Since the minimum is 4, this effectively means that
16-byte SIMD16 data alignment requests are ignored. This is likely
because this code was written before arm64 supported SIMD, and was
never revised.

Cases of SIMD loads of constant data lead to larger alignment
padding of the data section. This is somewhat mitigated by
dotnet#71043 which fixes a bug with overallocation
and overalignment of SIMD8 data loads.

Author: BruceForstall

src/coreclr/jit/emit.cpp

@@ -6330,11 +6330,9 @@ unsigned emitter::emitEndCodeGen(Compiler* comp,
     }
 
     UNATIVE_OFFSET roDataAlignmentDelta = 0;
-    if (emitConsDsc.dsdOffs && (emitConsDsc.alignment == TARGET_POINTER_SIZE))
+    if (emitConsDsc.dsdOffs > 0)
     {
-        UNATIVE_OFFSET roDataAlignment = TARGET_POINTER_SIZE; // 8 Byte align by default.
-        roDataAlignmentDelta = (UNATIVE_OFFSET)ALIGN_UP(emitTotalHotCodeSize, roDataAlignment) - emitTotalHotCodeSize;
-        assert((roDataAlignmentDelta == 0) || (roDataAlignmentDelta == 4));
+        roDataAlignmentDelta = AlignmentPad(emitTotalHotCodeSize, emitConsDsc.alignment);
     }
 
     args.hotCodeSize  = emitTotalHotCodeSize + roDataAlignmentDelta + emitConsDsc.dsdOffs;