Remove allocator check from BlobMemoryPool to avoid exceptions

Allocator validity for nullptr is checked during construction thus not
needed to be checked again during destruction.
Moreover, ARM_COMPUTE_ERROR_ON on failure throws an exception
that should be avoided by a destructor.

Signed-off-by: Georgios Pinitas <georgios.pinitas@arm.com>
Change-Id: Icd44f8af6824290a44c51d676a43a8f06555e158
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/5152
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/runtime/BlobMemoryPool.cpp b/src/runtime/BlobMemoryPool.cpp
index e3d7f0f..88e2805 100644
--- a/src/runtime/BlobMemoryPool.cpp
+++ b/src/runtime/BlobMemoryPool.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2020 Arm Limited.
+ * Copyright (c) 2017-2021 Arm Limited.
  *
  * SPDX-License-Identifier: MIT
  *
@@ -41,7 +41,6 @@
 
 BlobMemoryPool::~BlobMemoryPool()
 {
-    ARM_COMPUTE_ERROR_ON(!_allocator);
     free_blobs();
 }