[dxvk] Fix DxvkShaderPipelineLibraryKey::eq

It always returned true when comparing with empty key, resulting in
library from createNullFsPipelineLibrary()->compilePipeline() being
returned for non-empty key on some platforms.

Signed-off-by: Danylo Piliaiev <dpiliaiev@igalia.com>

Author: werman

src/dxvk/dxvk_shader.cpp

@@ -153,6 +153,9 @@ namespace dxvk {
 
   bool DxvkShaderPipelineLibraryKey::eq(
     const DxvkShaderPipelineLibraryKey& other) const {
+    if (m_shaders.size() != other.m_shaders.size())
+      return false;
+
     bool eq = true;
 
     for (uint32_t i = 0; i < m_shaders.size() && eq; i++)