Inline functions do not have an indentifiable return point and require
kernel built using VTA-enabled gcc to get tracking of variables. OTOH
syscall functions are very rarely inlined (depending on the compiler
mood), therefore filtering probes to include only non-inlined functions
ensures consistent behavior between different kernels.
This removes the problem of inaccessible variables in inlined syscalls
that is described in comments #6-9 to PR5890 and gives us the status quo
w.r.t. syscall probing, because before the commit solving PR10572
(b7478964) inline instances were masked anyway by non-inline ones.