video_core: commit the emulated-LDS allocation taken from the stream buffer (#5070)

The BufferType::SharedMemory path in Rasterizer::BindBuffers backs a compute
shader's LDS with a region of the stream buffer: it calls StreamBuffer::Map,
zeroes the bytes and binds them as the storage buffer the recompiler lowered
the LDS accesses to. It never called Commit.

Map only chooses the region and waits until it is free; Commit is what
reserves it. Commit flushes the host writes on non-coherent memory, advances
the ring cursor past the mapped bytes and records the completion watch that
makes a later wrap wait for the GPU work that used them. Without it the next
Map on the same stream buffer hands out the same bytes again, so a streamed
upload can overwrite the shader's shared memory while the dispatch that uses
it is in flight, and the shader's LDS stores can land in bytes a later upload
reads as its source.

Every other StreamBuffer::Map in the tree is paired with a Commit; this was
the only call site without one.

Co-authored-by: nikmparis217-ux <295578344+nikmparis217-ux@users.noreply.github.com>

src/video_core/renderer_vulkan/vk_rasterizer.cpp

@@ -764,6 +764,7 @@ void Rasterizer::BindBuffers(const Shader::Info& stage, Shader::Backend::Binding
                 const auto lds_size = cs_program.SharedMemSize() * cs_program.NumWorkgroups();
                 const auto [data, offset] = lds_buffer.Map(lds_size, alignment);
                 std::memset(data, 0, lds_size);
+                lds_buffer.Commit();
                 buffer_infos.emplace_back(lds_buffer.Handle(), offset, lds_size);
             } else {
                 UNREACHABLE_MSG("Unexpected buffer type {}", u32(desc.buffer_type));