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>

# Default test suite configuration

# Default DejaGnu configuration

DG_TOOLNAME = gcc

DG_TARGET_HOSTNAME = 127.0.0.1

DG_TARGET_USERNAME = root

# Default tests

DG_C_TESTS = 

DG_CPP_TESTS =