Our aligned_alloc(3) is C11, but more strict than on other platforms. Many tests
here fail with EINVAL if 'size' is not a multiple of 'alignment' _and_
alignment is not a power of 2. To better identify these cases, extend the error
message.

Index: tests/test_common.h
--- tests/test_common.h.orig
+++ tests/test_common.h
@@ -14,6 +14,7 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <errno.h>
 #include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -62,7 +63,7 @@ static void* blosc_test_malloc(const size_t alignment,
   void *block = NULL;
   int32_t res = 0;
 
-#if defined(_ISOC11_SOURCE) || (defined(__FreeBSD__) && __STDC_VERSION__ >= 201112L)
+#if defined(_ISOC11_SOURCE) || __STDC_VERSION__ >= 201112L
   /* C11 aligned allocation. 'size' must be a multiple of the alignment. */
   block = aligned_alloc(alignment, size);
 #elif defined(_WIN32)
@@ -79,7 +80,7 @@ static void* blosc_test_malloc(const size_t alignment,
 #endif
 
   if (block == NULL || res != 0) {
-    fprintf(stderr, "Error allocating memory!");
+    fprintf(stderr, "Error allocating memory: errno=%d, err_msg=\"%s\"\n", errno, strerror(errno));
     return NULL;
   }