feat(mem-alloc): add test visibility and magic constants

Add MEM_ALLOC_API_INTER macro for exposing internal functions
in test builds and magic value constants for aligned allocation
detection.

Author: lum1n0us

core/shared/mem-alloc/ems/ems_gc_internal.h

@@ -13,6 +13,15 @@ extern "C" {
 #include "bh_platform.h"
 #include "ems_gc.h"
 
+/* Test visibility macro for internal functions */
+#ifndef MEM_ALLOC_API_INTER
+#ifdef WAMR_BUILD_TEST
+#define MEM_ALLOC_API_INTER
+#else
+#define MEM_ALLOC_API_INTER static
+#endif
+#endif
+
 /* HMU (heap memory unit) basic block type */
 typedef enum hmu_type_enum {
     HMU_TYPE_MIN = 0,
@@ -87,6 +96,10 @@ hmu_verify(void *vheap, hmu_t *hmu);
     GC_ALIGN_8(HMU_SIZE + OBJ_PREFIX_SIZE + OBJ_SUFFIX_SIZE \
                + (((x) > 8) ? (x) : 8))
 
+/* Magic value for aligned allocation detection */
+#define ALIGNED_ALLOC_MAGIC_MASK   0xFFFF0000
+#define ALIGNED_ALLOC_MAGIC_VALUE  0xA11C0000
+
 /**
  * hmu bit operation
  */