Remove MEM_HEAP_PTR_64 macro

MEM_HEAP_PTR_64 is duplicating existing information: stdint.h, which
header is already used by the project, defines various _MAX macros
for upper limits of integer types. The comparison of UINTPTR_MAX and
UINT32_MAX can give the same info as encoded in MEM_HEAP_PTR_64.
The stdint.h-based approach has the benefit that jerry can support
any 64-bit architecture without the need for editing the build
system. (With the existing approach, CMakeLists has to know about
every 64-bit architecture to work properly.)

Thus, removing the extraneous macro from the code.

The patch also changes the mem_pools_chunk_t struct, as it turned
out that the struct does not have to be padded to MEM_POOL_CHUNK_SIZE.
(The padding also depended on MEM_HEAP_PTR_64.) It is enough if the
size of the struct is smaller than (or equal to) MEM_POOL_CHUNK_SIZE.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

jerry-core/mem/mem-heap.c

@@ -103,7 +103,7 @@ typedef struct
   uint32_t size; /* Size of region */
 } mem_heap_free_t;
 
-#ifdef MEM_HEAP_PTR_64
+#if UINTPTR_MAX > UINT32_MAX
 #define MEM_HEAP_GET_OFFSET_FROM_ADDR(p) ((uint32_t) ((uint8_t *) (p) - (uint8_t *) mem_heap.area))
 #define MEM_HEAP_GET_ADDR_FROM_OFFSET(u) ((mem_heap_free_t *) &mem_heap.area[u])
 #else