MeshTools: explicitly use default array deleters in copy().

To make sure it can be used in plugin implementations.

src/Magnum/MeshTools/Copy.cpp

@@ -138,7 +138,9 @@ Trade::MeshData copy(Trade::MeshData&& mesh) {
     /* Otherwise we have to allocate a new one and re-route the attributes to
        a potentially different vertex array */
     } else {
-        attributeData = Containers::Array<Trade::MeshAttributeData>{originalAttributeData.size()};
+        /* Using DefaultInit so the array has a default deleter and isn't
+           problematic to use in plugins */
+        attributeData = Containers::Array<Trade::MeshAttributeData>{DefaultInit, originalAttributeData.size()};
         for(std::size_t i = 0; i != originalAttributeData.size(); ++i) {
             attributeData[i] = Trade::MeshAttributeData{
                 originalAttributeData[i].name(),

src/Magnum/MeshTools/Test/CopyTest.cpp

@@ -124,6 +124,14 @@ void CopyTest::copy() {
 
     CORRADE_COMPARE_AS(copy.indexData(), cube.indexData(), TestSuite::Compare::Container);
     CORRADE_COMPARE_AS(copy.vertexData(), cube.vertexData(), TestSuite::Compare::Container);
+
+    /* The data should have a default deleter to make this usable in plugins */
+    Containers::Array<char> indexData = copy.releaseIndexData();
+    Containers::Array<char> vertexData = copy.releaseVertexData();
+    Containers::Array<Trade::MeshAttributeData> attributeData = copy.releaseAttributeData();
+    CORRADE_VERIFY(!indexData.deleter());
+    CORRADE_VERIFY(!vertexData.deleter());
+    CORRADE_VERIFY(!attributeData.deleter());
 }
 
 void CopyTest::copyNoIndexData() {