Utilities: Fix off by one error in uniq

Flags that rely on counting lines (-c and -d) were
producing results that were off by one. This is fixed
by initializing the `count` variable to 1, which is
consistent with behavior in the main loop, where it
is reset to 1 when lines don't match.

Tests/Utilities/TestUniq.cpp

@@ -50,3 +50,13 @@ TEST_CASE(long_line)
 
     run_uniq({}, StringView { input }, StringView { expected_output });
 }
+
+TEST_CASE(duplicate_flag)
+{
+    run_uniq({ "-d" }, "AAA\nAAA\nBBB\n"sv, "AAA\n"sv);
+}
+
+TEST_CASE(count_flag)
+{
+    run_uniq({ "-c" }, "AAA\nAAA\n"sv, "2 AAA\n"sv);
+}

Userland/Utilities/uniq.cpp

@@ -83,7 +83,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto infile = TRY(Core::InputBufferedFile::create(TRY(Core::File::open_file_or_standard_stream(inpath, Core::File::OpenMode::Read))));
     auto outfile = TRY(Core::File::open_file_or_standard_stream(outpath, Core::File::OpenMode::Write));
 
-    size_t count = 0;
+    // The count starts at 1 since each line will appear at least once.
+    // Otherwise the -d and -c flags do not work as expected.
+    size_t count = 1;
     ByteBuffer previous_buf = TRY(ByteBuffer::create_uninitialized(1024));
     ByteBuffer current_buf = TRY(ByteBuffer::create_uninitialized(1024));