Fix missing alignment in calloc() and realloc()

The calloc() and realloc() implementations did not align the requested
size before passing it to the allocator. This could result in returning
non-aligned memory blocks, which may trigger unaligned memory access
exceptions on RISC-V.

Align the total size in calloc() and the input size in realloc() to
ensure the allocator always returns properly aligned memory.

Author: visitorckw

lib/malloc.c

@@ -211,7 +211,7 @@ void *calloc(uint32_t nmemb, uint32_t size)
     if (unlikely(nmemb && size > MALLOC_MAX_SIZE / nmemb))
         return NULL;
 
-    uint32_t total_size = nmemb * size;
+    uint32_t total_size = ALIGN4(nmemb * size);
     void *buf = malloc(total_size);
 
     if (buf)
@@ -234,6 +234,8 @@ void *realloc(void *ptr, uint32_t size)
         return NULL;
     }
 
+    size = ALIGN4(size);
+
     memblock_t *old_block = ((memblock_t *) ptr) - 1;
 
     /* Validate the existing block */