Check for empty string in outcome file name

Signed-off-by: gabor-mezei-arm <gabor.mezei@arm.com>
diff --git a/tests/suites/host_test.function b/tests/suites/host_test.function
index 9dde6c2..db65c0f 100644
--- a/tests/suites/host_test.function
+++ b/tests/suites/host_test.function
@@ -551,7 +551,7 @@
         return( 1 );
     }
 
-    if( outcome_file_name != NULL )
+    if( outcome_file_name != NULL && *outcome_file_name != '\0' )
     {
         outcome_file = fopen( outcome_file_name, "a" );
         if( outcome_file == NULL )