tracing: Add alignment to syscall metadata declarations
For some reason if we declare a static variable and then assign it
later, and the assignment contains a __attribute__((__aligned__(#))),
some versions of gcc will ignore it.
This caused the syscall meta data to not be compact in its section
and caused a kernel oops when the section was being read.
The fix for these versions of gcc seems to be to add the aligned
attribute to the declaration as well.