DynamicLoader: Calulate max loaded file count based on dtv size

dtv should be dynamic but i dont care right now :)

userspace/libraries/LibC/include/pthread.h

@@ -51,7 +51,7 @@ struct uthread
 	int cancel_state;
 	int canceled;
 	// FIXME: make this dynamic
-	uintptr_t dtv[1 + 128];
+	uintptr_t dtv[1 + 256];
 };
 
 #define PTHREAD_CANCELED				(void*)1

userspace/programs/DynamicLoader/main.cpp

@@ -207,7 +207,7 @@ struct LoadedElf
 	const uint8_t* real_strtab_addr;
 };
 
-static constexpr size_t s_max_loaded_files = 128;
+static constexpr size_t s_max_loaded_files = sizeof(uthread::dtv) / sizeof(*uthread::dtv) - 1;
 static LoadedElf s_loaded_files[s_max_loaded_files];
 static size_t s_loaded_file_count = 0;