* sdbout.c (current_file): New global.
	(PUT_SDB_SRC_FILE): New PUT_SDB_FOO macro.
	(sdbout_init): Initialize current_file ifdef MIPS_DEBUGGING_INFO.
	(sdbout_{start_new,resume_previous}_source_file): New functions.
	* toplev.c (debug_{start,end}_source_file): Call them if SDB_DEBUG.
	* mips/mips.h (PUT_SDB_SRC_FILE): Define.

From-SVN: r13179