Fix setting breakpoints or stepping on line 65535

Fix setting breakpoints or stepping on line 65535

This removes code that was present from the very first git revisison
7b4ac7e1ed2c4616bce56d1760807798be87ac9e from 1988.  It was in the
gdb/dbxread.c at the time (and makes more sense for dbx line info format
since line numbers are 16-bit entities in that debug format and debugging
files with more than 65535 lines would not work anyway) but moved from
there to gdb/buildsym.c which is used for dwarf line info as well, and
excluding an arbitrary line number does certainly not make sense nowadays.

Add a test case for line 65535

gdb:
2019-12-29  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* buildsym.c (buildsym_compunit::record_line): Do no longer ignore
	line 65535.

gdb/testsuite:
2019-12-29  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* gdb.base/line65535.exp: New file.
	* gdb.base/line65535.c: New file.