COMPMID-3067: Address gcc9 failures

Signed-off-by: Georgios Pinitas <georgios.pinitas@arm.com>
Change-Id: I048d1d7dda7edf587d37ce83a93b557d8a95754a
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/2771
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
diff --git a/arm_compute/runtime/MemoryGroup.h b/arm_compute/runtime/MemoryGroup.h
index ba1dbc0..4d48495 100644
--- a/arm_compute/runtime/MemoryGroup.h
+++ b/arm_compute/runtime/MemoryGroup.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2019 ARM Limited.
+ * Copyright (c) 2017-2020 ARM Limited.
  *
  * SPDX-License-Identifier: MIT
  *
@@ -44,9 +44,7 @@
 {
 public:
     /** Default Constructor */
-    MemoryGroup(IMemoryManager *memory_manager);
-    /** Default Constructor */
-    MemoryGroup(std::shared_ptr<IMemoryManager> = nullptr);
+    MemoryGroup(std::shared_ptr<IMemoryManager> = nullptr) noexcept;
     /** Default destructor */
     ~MemoryGroup() = default;
     /** Prevent instances of this class from being copied (As this class contains pointers) */
@@ -71,8 +69,10 @@
     MemoryMappings                  _mappings;       /**< Memory mappings of the group */
 };
 
-inline MemoryGroup::MemoryGroup(std::shared_ptr<IMemoryManager> memory_manager)
-    : _memory_manager(memory_manager), _pool(nullptr), _mappings()
+inline MemoryGroup::MemoryGroup(std::shared_ptr<IMemoryManager> memory_manager) noexcept
+    : _memory_manager(memory_manager),
+      _pool(nullptr),
+      _mappings()
 {
 }