debug/gdb: add option to enable/disable the IPA lib for gdbserver

gdbserver >= 7.2 comes with an optional library to use tracepoints, the
In Process Agent (IPA) library, libinproctrace.so.

Currently, we build gdbserver staticaly, but that breaks the build of
the IPA lib.

Add an option to biuld the IPA lib, but not if statically linking.

Reported-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

 # Bare metal config options

 ## select BARE_METAL

 ##

 ## help 'Bare metal' refers to those programs that run without any kernel.

 ## help

 ## help You probably want to say 'y' here if you plan to use your compiler

 ## help to build bootloaders. It is not yet suitable to build Linux kernels,

 ## help though, because the APCI stuff relies on the target C library headers

 ## help being available?!?!...