add $(Beremiz installation)/mingw/bin in PATH on Windows platform

This fixes issue if multiple gcc installation are found in user's
PATH. Now gcc from Beremiz is used by default.

[TOPOLOGY]
NetName=None
Nodes=0x01
Node2Present=0x01
Node2Name=SlaveNode
Node2DCFName=Slave_0_0.eds
EDSBaseName=eds