Description:
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On non-ZTS builds, PHP segfaults if opcache.interned_strings_buffer=0.  This is because bult-in initialisation assumes that the PHP interned_string pool can be succcessfully copied to SHM.  

As with the opcache.memory_consumption and opcache.max_accelerated_files INI parameters, opcache.interned_strings_buffer should have a validated minimum.  In this case of 1 (Mb).

Test script:
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php56 -d opcache.enable=1 -d opcache.enable_cli=1 -d opcache.interned_strings_buffer=0 -r ''


Expected result:
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PHP should gracefully handle any valid INI parameter

Actual result:
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You get a Segfault.