arch: Add vec_reg.test & vec_pred_reg.test unittests

Change-Id: Ieb85e0d35032585ead1e3b399f8eaf5dbc246d76
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/44508
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/arch/generic/SConscript

@@ -50,6 +50,9 @@ DebugFlag('PageTableWalker',
           "Page table walker state machine debugging")
 DebugFlag('TLB')
 
+GTest('vec_reg.test', 'vec_reg.test.cc')
+GTest('vec_pred_reg.test', 'vec_pred_reg.test.cc')
+
 if env['TARGET_ISA'] == 'null':
     Return()