__aligned() is a shorthand that is only available in the kernel space
because it is defined in include/linux/compiler_attributes.h, which is
not exported to the user space.
Detected by compile-testing exported headers.
./usr/include/asm/runtime_instr.h:60:37: error: expected declaration specifiers or ‘...’ before numeric constant
} __attribute__((packed)) __aligned(8);
^