noux: construct new child only if binary is valid

If a script is executed which uses a interpreter that does not exist the
construction of the child fails and potentially leaks memory because the
wrong delete operator is called.
Therefore the binary dataspace of the script and the binary dataspace of
the interpreter are now checked before a new child will be created.

Fixes #812.
noux: short-cut for read(..., 0)

If the bytes left to read are 0 we drop out early w/o involving the
packet-stream.
noux: increase the stack size of rpc-ep thread

The current limit (4/8 KiB) is too small when tracing will be enabled.
core: add session label member

This member is used to save the actual session label for further use
within core.
base: add name accessor method to RPC struct

This method may be used to get the actual name of the
corresponding RPC-function.
base: add serialized rdtsc function

Use cpuid instruction to prevent the cpu from reordering the rdtsc
instruction when obtaining the TSC value.

Though it is questionable if "mfence; rdtsc" or "rdtscp" would be
a better choice.
base: add Trace API header

This includes the Trace_buffer declaration and definition of most
common functions used to access the buffer and policy.
base: add Trace_session header
core: add Trace_session_component
base: add trace accessors to Thread_base interface
base: add tb_dataspace() to Cpu_session interface
base: add tb_dataspace() to Expanding_c_s_c
core: add TRACE
base: add trace startup-code to _main()
linux: add Expanding_cpu_session_client
linux: add Trace_session_component
linux: initial Trace_session support
foc: add trace_session_component to target.inc
foc: add trace_buffer Cpu_session interface
foc: add trace_buffer start-up to Thread_base