Add testcase() macros beside each sqlite3_log() call to make sure it is

tested with both logging enable and disabled.

FossilOrigin-Name: 1168763d2cd96acfa0488198e8bc82f0c4fa35a3

src/mem5.c

@@ -269,6 +269,7 @@ static void *memsys5MallocUnsafe(int nByte){
   */
   for(iBin=iLogsize; mem5.aiFreelist[iBin]<0 && iBin<=LOGMAX; iBin++){}
   if( iBin>LOGMAX ){
+    testcase( sqlite3GlobalConfig.xLog!=0 );
     sqlite3_log(SQLITE_NOMEM, "failed to allocate %u bytes", nByte);
     return 0;
   }