Fixed memory leak reading JPEG metadata

[MajorMurphy]

After calling ImageMetadata::getFromImage for a JPEG file, a memory leak was being reported.

Detected memory leaks! Dumping objects -> {26326} normal block at 0x00000255720A4E80, 16312 bytes long. Data: < > 00 00 00 00 00 00 00 00 20 01 00 00 00 00 00 00 {26325} normal block at 0x0000025571CD40F0, 32224 bytes long. Data: < & qU } > F0 26 F4 71 55 02 00 00 C8 7D 00 00 00 00 00 00 {26324} normal block at 0x0000025571F426F0, 1320 bytes long. Data: < 8uU > 00 98 38 75 55 02 00 00 10 05 00 00 00 00 00 00 {26323} normal block at 0x0000025575389800, 672 bytes long. Data: < ^!uU > F0 5E 21 75 55 02 00 00 88 02 00 00 00 00 00 00 {26322} normal block at 0x0000025575215EF0, 72 bytes long. Data: < 2ojU 0 > 10 32 6F 6A 55 02 00 00 30 00 00 00 00 00 00 00 {26321} normal block at 0x000002556A6F3210, 1192 bytes long. Data: < > 00 00 00 00 00 00 00 00 90 04 00 00 00 00 00 00 {26320} normal block at 0x0000025571D35E60, 1888 bytes long. Data: < > 00 00 00 00 00 00 00 00 E0 06 00 00 00 00 00 00 {26319} normal block at 0x0000025571EFFBE0, 152 bytes long. Data: < > A0 E7 C6 1F F6 7F 00 00 90 EA C6 1F F6 7F 00 00 Object dump complete.

Looking at loadJPEGMetadataFromStream, jpeg_create_decompress seemed to need a closing call to jpeg_destroy_decompress.

Adding this function call resolved the reported memory leak.