IVGCVSW-6344 Remove definition of CapabilityTestHelper if no backends are enabled

Signed-off-by: Finn Williams <Finn.Williams@arm.com>
Change-Id: I97b3302204e6a576220c800e21c5d031c84819a5
diff --git a/src/backends/backendsCommon/test/CompatibilityTests.cpp b/src/backends/backendsCommon/test/CompatibilityTests.cpp
index 7b25732..ff842e9 100644
--- a/src/backends/backendsCommon/test/CompatibilityTests.cpp
+++ b/src/backends/backendsCommon/test/CompatibilityTests.cpp
@@ -132,6 +132,7 @@
 namespace
 {
 
+#if defined(ARMNNREF_ENABLED) || defined(ARMCOMPUTENEON_ENABLED) || defined(ARMCOMPUTECL_ENABLED)
 void CapabilityTestHelper(BackendCapabilities &capabilities,
                           std::vector<std::pair<std::string, bool>> capabilityVector)
 {
@@ -143,6 +144,7 @@
                         pair.first << " capability set incorrectly");
     }
 }
+#endif
 
 #if defined(ARMNNREF_ENABLED)