loader, icd: correct use of _aligned_malloc

Memory allocated with _aligned_malloc on WIN32 should be released with _aligned_free.
If icd/common/icd-instance is ever used on WIN32 it will now use _aligned_free.

loader_aligned_heap_alloc and loader_aligned_alloc would require additional
matching loader_aligned*_free functions to be correct for WIN32.
But both functions are never used.  Just remove those functions for now.
diff --git a/icd/common/icd-instance.c b/icd/common/icd-instance.c
index 3568b76..b792048 100644
--- a/icd/common/icd-instance.c
+++ b/icd/common/icd-instance.c
@@ -58,7 +58,11 @@
 
 static void VKAPI default_free(void *user_data, void *ptr)
 {
+#if defined(_WIN32)
+    _aligned_free(ptr);
+#else
     free(ptr);
+#endif
 }
 
 struct icd_instance *icd_instance_create(const VkApplicationInfo *app_info,