gbproxy: /bin/sh cannot do "FILES+=", use /bin/bash

This fixes an ugly copile failure depending on which shell
provides /bin/sh on the given system:

AF_PACKET_PortType.so: undefined reference to `typeinfo for AF__PACKET__PortType::AF__PACKET__PT_PROVIDER'
AF_PACKET_PortType.so: undefined reference to `AF__PACKET__PortType::AF__PACKET__PT_PROVIDER::AF__PACKET__PT_PROVIDER(char const*)'
AF_PACKET_PortType.so: undefined  [0m [91mreference to `AF__PACKET__PortType::AF__PACKET__PT_PROVIDER::set_parameter(char const*, char const [0m [91m*)'
AF_PACKET_PortType.so: undefined reference to `AF__PACKET__PortType::AF__PACKET__PT_PROVIDER::outgoing_send(AF__PACKET__PortTypes::AF__PACKET__Unitdata const&)' [0m [91m
AF_PACKET_PortType.so: undefined reference to `AF__PACKET__PortType::AF__PACKET__PT_PROVIDER::user_map(char [0m [91m const*, Map_Params& [0m [91m)' [0m [91m
AF_PACKET_PortType.so:  [0m [91mundefined reference to [0m [91m `AF__PACKET__PortType:: [0m [91mAF__PACKET__PT_PROVIDER::user_unmap(char const*, Map_Params&)'
AF_PACKET_PortType.so: undefined reference to ` [0m [91mAF__PACKET__PortType::AF__PACKET__PT_PROVIDER:: [0m [91m~AF__PACKET__PT_PROVIDER()' [0m [91m
AF_PACKET_PortType.so [0m [91m: undefined reference  [0m [91mto ` [0m [91mAF__PACKET__PortType::AF__PACKET__PT_PROVIDER::Handle_Fd_Event(int, bool, bool, bool) [0m [91m'
AF_PACKET_PortType.so:  [0m [91mundefined  [0m [91mreference to [0m [91m `AF__PACKET__PortType: [0m [91m:AF__PACKET__PT_PROVIDER::user_start()'

Change-Id: I71352f5fa538c3ba599b11c2bb1fec2952ddbf80

gbproxy/regen_makefile.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 
 FILES="*.ttcn *.ttcnpp BSSGP_EncDec.cc LLC_EncDec.cc IPL4asp_PT.cc IPL4asp_discovery.cc TCCConversion.cc TCCInterface.cc NS_CodecPort_CtrlFunctDef.cc RLCMAC_EncDec.cc Native_FunctionDefs.cc TELNETasp_PT.cc IPA_CodecPort_CtrlFunctDef.cc GTPU_EncDec.cc GTPC_EncDec.cc GTP_CodecPort_CtrlFunctDef.cc SCCP_EncDec.cc  SCTPasp_PT.cc "
 FILES+="AF_PACKET_PT.cc AF_PACKET_PT.hh "