[FS#1464] Perl built with gcc > v5 segfaults on apm821xx

[LEDE Bugs]

The following task has a new comment added:

FS#1464 - Perl built with gcc > v5 segfaults on apm821xx
User who did this - Christian Lamparter (chunkeey)

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[[https://github.com/arsv/perl-cross/issues/60|perl-cross issue #60]] suggests that the gcc version detection code broke. arsv mentioned a fix and it seems that manually forcing "-fwrapv -fno-strict-aliasing" did the trick here. (See attached patch.)

I had to completely purge the old perl installation too. the --force-reinstall did not on local packages.
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More information can be found at the following URL:
https://bugs.openwrt.org/index.php?do=details&task_id=1464#comment4544