This avoids a conflict with recent 20230802.1 where libintl.h
 functions get included into :: before we can include it in
 telephony-service code.

 This namespace mismatch only shows up with libtelephonyservice/
 contactwatcher.cpp, indicator/messagingmenu.cpp, indicator/
 authhandler.cpp and maybe others. To make the include statements
 uniform across all of the telephony-service code, the C:: namespace
 inclusion of libintl.h functions has been dropped in all code files
 of telephony-service.