Use fallback aligned_alloc for older glibc++

This function was introduced in C++17, then backported to older versions
of glibc++ library, but is not available in older releases (it's missing
from Ubuntu 12.04 derived SteamRT for example).

src/vk_mem_alloc.h

@@ -3302,7 +3302,7 @@ void *aligned_alloc(size_t alignment, size_t size)
 
     return memalign(alignment, size);
 }
-#elif defined(__APPLE__) || defined(__ANDROID__)
+#elif defined(__APPLE__) || defined(__ANDROID__) || (defined(__GLIBCXX__) && !defined(_GLIBCXX_HAVE_ALIGNED_ALLOC))
 #include <cstdlib>
 void *aligned_alloc(size_t alignment, size_t size)
 {