Fix compiler warnings about using characters that are not valid UTF-8 in comments

src/common/filesystem/source/file_directory.cpp

@@ -132,7 +132,7 @@ int FDirectory::AddDirectory(const char *dirpath, LumpFilterInfo* filter, FileSy
 					// On Linux this is important because its file system is case sensitive,
 					// but even on Windows the Unicode normalization is destructive 
 					// for some characters and cannot be used for file names.
-					// Examples for this are the Turkish 'i's or the German ß.
+					// Examples for this are the Turkish 'i's or the German scharfes s.
 					SystemFilePath[count] = stringpool->Strdup(entry.FilePathRel.c_str());
 					// for internal access we use the normalized form of the relative path.
 					// this is fine because the paths that get compared against this will also be normalized.

src/common/rendering/hwrenderer/data/hw_collision.cpp

@@ -285,7 +285,7 @@ float TriangleMeshShape::intersect_triangle_ray(TriangleMeshShape *shape, const
 		shape->vertices[shape->elements[start_element + 2]].fPos()
 	};
 
-	// Moeller–Trumbore ray-triangle intersection algorithm:
+	// Moeller-Trumbore ray-triangle intersection algorithm:
 
 	FVector3 D = ray.end - ray.start;