code: Use std::span where appropriate (#6658)

* code: Use std::span when possible

* code: Prefix memcpy and memcmp with std::

src/core/loader/elf.cpp

@@ -327,7 +327,7 @@ std::shared_ptr<CodeSet> ElfReader::LoadInto(u32 vaddr) {
             codeset_segment->addr = segment_addr;
             codeset_segment->size = aligned_size;
 
-            memcpy(&program_image[current_image_position], GetSegmentPtr(i), p->p_filesz);
+            std::memcpy(&program_image[current_image_position], GetSegmentPtr(i), p->p_filesz);
             current_image_position += aligned_size;
         }
     }