[FIX] Fix minor memory leak in OCR code

[kdrag0n]

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This leak was detected by Valgrind:

==1203168== 2,880 bytes in 57 blocks are definitely lost in loss record 3 of 4
==1203168==    at 0x483877F: malloc (vg_replace_malloc.c:309)
==1203168==    by 0x51ADBEE: strdup (in /usr/lib/libc-2.30.so)
==1203168==    by 0x24D1F8: ocr_bitmap (ocr.c:569)
==1203168==    by 0x24E25B: ocr_rect (ocr.c:907)
==1203168==    by 0x284832: write_dvb_sub (dvb_subtitle_decoder.c:1665)
==1203168==    by 0x284B7A: dvbsub_handle_display_segment (dvb_subtitle_decoder.c:1720)
==1203168==    by 0x285024: dvbsub_decode (dvb_subtitle_decoder.c:1828)
==1203168==    by 0x2406AF: process_data (general_loop.c:648)
==1203168==    by 0x2416D0: general_loop (general_loop.c:1025)
==1203168==    by 0x1AC89A: api_start (ccextractor.c:214)
==1203168==    by 0x16EC03: main (ccextractor.c:536)

[ccextractor-bot]

CCExtractor CI platform finished running the test files on linux. Below is a summary of the test results:

Report Name	Tests Passed
Broken	13/13
DVB	3/7
DVR-MS	2/2
General	27/27
Hauppage	3/3
MP4	3/3
NoCC	10/10
Teletext	15/21
WTV	12/13
XDS	34/34
CEA-708	14/14
DVD	3/3
Options	82/86

It seems that not all tests were passed completely. This is an indication that the output of some files is not as expected (but might be according to you).

Your PR breaks these cases:

• ccextractor -datapid 5603 -autoprogram -out=srt -latin1 -teletext 85c7fc1ad7...
• ccextractor -autoprogram -out=srt -latin1 85271be4d2...
• ccextractor -autoprogram -out=ttxt -latin1 c0d2fba8c0...
• ccextractor -autoprogram -out=ttxt -latin1 27d7a43dd6...
• ccextractor -autoprogram -out=ttxt -latin1 efbe129086...
• ccextractor -autoprogram -out=ttxt -latin1 e2e2b501e0...
• ccextractor -autoprogram -out=ttxt -latin1 -datets dcada745de...
• ccextractor -autoprogram -out=srt -latin1 -teletext -tpage 398 3b276ad8bf...
• ccextractor -out=srt -latin1 f23a544ba8...
• ccextractor -608 -out=srt c83f765c66...
• ccextractor -tpage 801 4e56e88ba4...
• ccextractor -tverbose 4e56e88ba4...
• ccextractor -teletext 4e56e88ba4...
• ccextractor -stdout -quiet -nofc 79a51f3500...
• ccextractor -stdout -quiet -nofc 767b546f96...

Check the result page for more info.

[ccextractor-bot]

CCExtractor CI platform finished running the test files on windows. Below is a summary of the test results:

Report Name	Tests Passed
Broken	13/13
DVB	4/7
DVR-MS	2/2
General	27/27
Hauppage	3/3
MP4	3/3
NoCC	10/10
Teletext	21/21
WTV	13/13
XDS	33/34
CEA-708	14/14
DVD	3/3
Options	85/86

It seems that not all tests were passed completely. This is an indication that the output of some files is not as expected (but might be according to you).

Your PR breaks these cases:

• ccextractor -autoprogram -out=srt -latin1 85271be4d2...
• ccextractor -autoprogram -out=smptett -latin1 -ucla e274a73653...
• ccextractor --capfile /repository/Dictionary/MattS_dictionary.txt c83f765c66...
• ccextractor -stdout -quiet -nofc 79a51f3500...
• ccextractor -stdout -quiet -nofc 767b546f96...

Check the result page for more info.