make dsptool fail if input file path doesn't exist

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@3245 8ced0084-cf51-0410-be5f-012b33b47a6e

Source/DSPTool/Src/main.cpp

@@ -248,6 +248,11 @@ int main(int argc, const char *argv[])
 				return 1;
 			}
 			input_name = argv[i];
+			if (!File::Exists(input_name.c_str()))
+			{
+				printf("Input path does not exist.\n");
+				return 1;
+			}
 		}
 	}