HHVM 3.26.1

HHVM 3.26.1 is released! This release contains several bugfixes, primarily improving support for PHP code when using HackC:

• ext_factparse: return empty lists instead of null for empty files
• HackC: fix is_array() and similar checks for superglobals
• HackC: fix isset() for superglobals
• HackC: fix if statements with empty bodies when using the if(0): endif; syntax
• HackC: fix support for nested array elements as inout parameters
• HackC: fix support for unicode identifiers (e.g. property names)
• HackC: fix support for class/enum constants as shape keys in namespaces
• HackC: fix case-insensitivity of PHP keywords