newlib C aligned_alloc implementation issue

[davidsj2]

The implementation aligned_alloc for newlib C library appears to make use of posix_memalign for some targets (tested riscv and leon3 qemu targets), which doesn't exist. This leads to undefined references:

aligned_alloc.c:(.text.aligned_alloc+0xa): undefined reference to `posix_memalign'
collect2: error: ld returned 1 exit status

Currently using SDK version 0.16.1 and latest Zephyr master revision (0df085b)

[m-torhan]

Did you define CONFIG_HEAP_MEM_POOL_SIZE in your project config?