[FS#1003] Flex does not build with GCC 7.2

[LEDE Bugs]

The following task has a new comment added:

FS#1003 - Flex does not build with GCC 7.2
User who did this - MartB (MartB)

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Dang should have pulled i was not paying attention to the commits today. Thanks for pointing that out.
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=1003#comment3497