detect/base64: remove unused macro warning

when compiling without unit tests
detect-transform-base64.c:47:9: warning: macro is not used [-Wunused-macros]
   47 | #define DETECT_TRANSFORM_FROM_BASE64_MODE_DEFAULT (uint8_t) Base64ModeRFC4648

src/detect-transform-base64.c

@@ -40,12 +40,11 @@
 static int DetectTransformFromBase64DecodeSetup(DetectEngineCtx *, Signature *, const char *);
 static void DetectTransformFromBase64DecodeFree(DetectEngineCtx *, void *);
 #ifdef UNITTESTS
+#define DETECT_TRANSFORM_FROM_BASE64_MODE_DEFAULT (uint8_t) Base64ModeRFC4648
 static void DetectTransformFromBase64DecodeRegisterTests(void);
 #endif
 static void TransformFromBase64Decode(InspectionBuffer *buffer, void *options);
 
-#define DETECT_TRANSFORM_FROM_BASE64_MODE_DEFAULT (uint8_t) Base64ModeRFC4648
-
 void DetectTransformFromBase64DecodeRegister(void)
 {
     sigmatch_table[DETECT_TRANSFORM_FROM_BASE64].name = "from_base64";