added option to disable the test unit

gex.mk

@@ -105,3 +105,7 @@ GEX_SRC_DIR += \
     User/vfs
 
 endif
+
+ifeq '$(DISABLE_TEST_UNIT)' '1'
+GEX_CDEFS += -DDISABLE_TEST_UNIT
+endif

platform/platform.c

@@ -22,7 +22,10 @@ void plat_init_resources(void)
 
     // --- Common unit drivers ---
     ureg_add_type(&UNIT_PIN);
-    ureg_add_type(&UNIT_TEST);
+
+    #if !DISABLE_TEST_UNIT
+        ureg_add_type(&UNIT_TEST);
+    #endif
 
     // --- platform specific resource releases and claims ---