aligned malloc() in GCC?
Since the question was asked, a new function was standardized by C11:
void *aligned_alloc(size_t alignment, size_t size);
and it is available in glibc (not on windows as far as I know). It takes its arguments in the same order as memalign, the reverse of Microsoft's _aligned_malloc, and uses the same free function as usual for deallocation.
A subtle difference is that aligned_alloc requires size to be a multiple of alignment.
See the memalign family of functions.