freetdm: refactor ftmod_gsm.c code to use proper core functions and interrupts to wait for io and state changes

         - Add definition of FTDM_MAX_SIG_PARAMETERS to have a standard limit for signaling module parameters

Conflicts:
	libs/freetdm/src/ftmod/ftmod_sangoma_isdn/ftmod_sangoma_isdn_stack_rcv.c
	libs/freetdm/src/ftmod/ftmod_sangoma_isdn/ftmod_sangoma_isdn_support.c

FS-3768 Mutex lock missing.  I would personally removed that lock since all the sql call does lock it now.  But maybe it required that no other request be done in the mean time.

add sofia global standby on that makes sofia not do anything but refuse to work until sofia global standby off or sofia recover is issued

I've had to add a missing include and do some formating cleanup.

NOTE: This patch might affect xml_cdr, so better check if the output is to your liking after this commit

Please Windows user test this one out.