(record_line): Record directly in a subfile. Alloc on demand.
(compare_line_numbers): Add from xcoffread.c.
(end_symtab): New params say whether to sort pendings and
linetable. Patch block stabs if defined. Shrink linetable before
allocating the symtab.
* buildsym.h: Delete line_vector* and prev_line_number. Add
global_stabs and file_stabs for xcoffread.
* dbxread.c (start_subfile): Move to buildsym. Change above calls.
* symtab.h: LINETABLE(symtab) can now be null. Zap LINELIST.
* symmisc.c, symtab.c: Cope with null LINETABLEs.
