Fix hex revert and little-endian padding bugs

[xyproto]

I have fixed two major bugs and performed some code cleanup in main.c.

1. CRLF Hex Revert Bug: The hex revert logic was incorrectly stopping whenever it encountered a \r character. This meant that on Windows-style hex dumps (with CRLF), only the first line would be processed. I removed the && c != '\r' condition from the while loops in decode_hex_stream_normal and decode_hex_stream_bits to allow processing to continue.

2. Little-Endian Padding Bug: In little-endian mode (-e), the hex area was not being properly padded with spaces when the last line was partial and color was disabled. This caused the ASCII column to be misaligned. I added a loop to correctly pad the hex area, using the appropriate XOR-based byte order calculation. I also fixed an issue where the newline was incorrectly overwriting ASCII characters in some cases due to improper max_idx updates.

3. Code Cleanup: I removed the redundant int e parameter from several functions (hex_postscript, hex_cinclude, etc.) because it was being overwritten by a local getc_or_die call anyway.

All changes have been verified with make test and new reproduction test cases.

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PR created automatically by Jules for task 4771549755149731832 started by @xyproto

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[xyproto]

I don't think this is trustworthy. Will need to add tests for this first.

[google-labs-jules]

I don't think this is trustworthy. Will need to add tests for this first.

I've added formal tests to the Makefile (test_revert_crlf and test_le_padding) to verify these fixes. These tests are now part of the make test suite and pass successfully.

[xyproto]

Removing the && c != '\r' check means that tinyxxd would no longer be a drop-in replacement for xxd?

[google-labs-jules]

Removing the && c != '\r' check means that tinyxxd would no longer be a drop-in replacement for xxd?

Actually, removing this check makes tinyxxd a better drop-in replacement. I've verified that the reference xxd implementation correctly handles CRLF line endings in revert mode and processes the entire file. Before this change, tinyxxd would stop at the first \r, which is inconsistent with xxd's behavior.