Fix OpenBSD build errors

* Partially resolves COMPMID-5396

Change-Id: I7f3e692e73da548a901a07ed6d7212df40b8c26f
Signed-off-by: Pablo Marquez Tello <pablo.tello@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/7870
Reviewed-by: Gunes Bayir <gunes.bayir@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Benchmark: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/core/NEON/kernels/arm_conv/pooling/pooling_depthfirst_generic.hpp b/src/core/NEON/kernels/arm_conv/pooling/pooling_depthfirst_generic.hpp
index 227d808..65d9a91 100644
--- a/src/core/NEON/kernels/arm_conv/pooling/pooling_depthfirst_generic.hpp
+++ b/src/core/NEON/kernels/arm_conv/pooling/pooling_depthfirst_generic.hpp
@@ -27,7 +27,9 @@
 #include "arm_compute/core/Error.h"
 #include "depthfirst_driver.hpp"
 #include "utils.hpp"
+#if !defined(_WIN64) && !defined(__OpenBSD__)
 #include <alloca.h>
+#endif /* !defined(_WIN64) && !defined(__OpenBSD__) */
 
 namespace arm_conv {
 namespace pooling {