Fix crash when loading multiple times from GDB
Fix crash when loading multiple times from GDB

Fix a crash caused by overlapping data in GDB server's flashBuilder
object by setting flashBuilder to none after it has been used.  With
this change the GDB server will create a new flash builder object
on the second load, and there will be no overlap.

This problem was introduced in the commit:
ecd0979967fe86747e8232357d7f7abfbd0531c2 -
Update gdbserver to support more generic programming

oliviermartin/pyOCD,oliviermartin/pyOCD,adamgreen/pyOCD,wjzhang/pyOCD,0xc0170/pyOCD,mbedmicro/pyOCD,mesheven/pyOCD,matthewelse/pyOCD,matthewelse/pyOCD,geky/pyDAPLink,tgarc/pyOCD,matthewelse/pyOCD,molejar/pyOCD,bridadan/pyOCD,flit/pyOCD,mesheven/pyOCD,devanlai/pyOCD,molejar/pyOCD,pyocd/pyOCD,pyocd/pyOCD,oliviermartin/pyOCD,wjzhang/pyOCD,devanlai/pyOCD,bridadan/pyOCD,tgarc/pyOCD,geky/pyOCD,bridadan/pyOCD,tgarc/pyOCD,mbedmicro/pyOCD,0xc0170/pyOCD,mbedmicro/pyOCD,adamgreen/pyOCD,c1728p9/pyOCD,c1728p9/pyOCD,devanlai/pyOCD,geky/pyOCD,molejar/pyOCD,adamgreen/pyOCD,mesheven/pyOCD,0xc0170/pyOCD,geky/pyOCDgdb,wjzhang/pyOCD,flit/pyOCD,c1728p9/pyOCD