Misc: fixed strict aliasing violation in ImHashData(). (#9557)

The SSE4.2 path read the input through an `ImU32` pointer but callers
hash floats, pointers and structs. With clang 23 and LTO (such as
`-O2 -msse4.2 -flto -fuse-ld=lld`) the float stores in
`ImFontAtlasBakedGetId()` were optimized away, so every size of a font
got the same `BakedId`.

imgui.cpp

@@ -2493,7 +2493,7 @@ ImGuiID ImHashData(const void* data_p, size_t data_size, ImGuiID seed)
 #else
     while (data + 4 <= data_end)
     {
-        crc = _mm_crc32_u32(crc, *(ImU32*)data);
+        ImU32 v; memcpy(&v, data, sizeof(v)); crc = _mm_crc32_u32(crc, v);
         data += 4;
     }
     while (data < data_end)