Improve test gdb.dwarf2/dw2-ranges-func.exp

Improve test gdb.dwarf2/dw2-ranges-func.exp

The original dw2-ranges-func.exp test caused a function named foo to be
created with two non-contiguous address ranges.  In the C source file,
a function named foo_low was incorporated into the function foo which
was also defined in that file.  The DWARF assembler is used to do this
manipulation.  The source file had been laid out so that foo_low would
likely be placed (by the compiler and linker) at a lower address than
foo().

The case where a range at a higher set of addresses (than foo) was not
being tested.  In a recent discussion on gdb-patches, it became clear
that performing such tests are desirable because bugs were discovered
which only became evident when the other range was located at high(er)
addresses than the range containing the entry point for the function.

This other (non entry pc) address range is typically used for "cold"
code which executes less frequently.  Thus, I renamed foo_low to
foo_cold and renamed the C source file from dw-ranges-func.c to
dw-ranges-func-lo.c.  I then made a copy of this file, naming it
dw-ranges-func-hi.c.  (That was my intent anyway.  According to git,
I renamed dw-ranges-func.c to dw-ranges-func-hi.c and then modified it.
dw-ranges-func-lo.c shows up as an entirely new file.)

Within dw-ranges-func-hi.c, I changed the placement of foo_cold()
along with some of the other functions so that foo_cold() would be at
a higher address than foo() while also remaining non-contiguous.  The
two files, dw-ranges-func-lo.c and dw-ranges-func-hi.c, are
essentially the same except for the placement of some of the functions
therein.

The tests in dw2-ranges-func.exp where then wrapped in a new proc named
do_test which was then called in a loop from the outermost level.  The
loop causes each of the source files to have the same tests run upon
them.

I also added a few new tests which test functionality fixed by the other
commits to this patch series.  Due to the reorganization of the file,
it's hard to identify these changes in the patch.  So, here are the
tests which were added:

    with_test_prefix "no-cold-names" {

	# Due to the calling sequence, this backtrace would normally
	# show function foo_cold for frame #1.  However, we don't want
	# this to be the case due to placing it in the same block
	# (albeit at a different range) as foo.  Thus it is correct to
	# see foo for frames #1 and #2.  It is incorrect to see
	# foo_cold at frame #1.
	gdb_test_sequence "bt" "backtrace from baz" {
	    "\[\r\n\]#0 .*? baz \\(\\) "
	    "\[\r\n\]#1 .*? foo \\(\\) "
	    "\[\r\n\]#2 .*? foo \\(\\) "
	    "\[\r\n\]#3 .*? main \\(\\) "
	}

	# Doing x/2i foo_cold should show foo_cold as the first symbolic
	# address and an offset from foo for the second.  We also check to
	# make sure that the offset is not too large - we don't GDB to
	# display really large offsets that would (try to) wrap around the
	# address space.
	set foo_cold_offset 0
	set test "x/2i foo_cold"
	gdb_test_multiple $test $test {
	    -re "   (?:$hex) <foo_cold>.*?\n   (?:$hex) <foo\[+-\](\[0-9\]+)>.*${gdb_prompt}" {
	        set foo_cold_offset $expect_out(1,string)
		pass $test
	    }
	}
	gdb_assert {$foo_cold_offset <= 10000} "offset to foo_cold is not too large"

	# Likewise, verify that second address shown by "info line" is at
	# and offset from foo instead of foo_cold.
	gdb_test "info line *foo_cold" "starts at address $hex <foo_cold> and ends at $hex <foo\[+-\].*?>.*"

    }

When run against a GDB without the requisite bug fixes (from this patch
series), these 6 failures should be seen:

FAIL: gdb.dwarf2/dw2-ranges-func.exp: lo-cold: no-cold-names: backtrace from baz (pattern 4)
FAIL: gdb.dwarf2/dw2-ranges-func.exp: lo-cold: no-cold-names: x/2i foo_cold
FAIL: gdb.dwarf2/dw2-ranges-func.exp: lo-cold: no-cold-names: info line *foo_cold
FAIL: gdb.dwarf2/dw2-ranges-func.exp: hi-cold: no-cold-names: backtrace from baz (pattern 3)
FAIL: gdb.dwarf2/dw2-ranges-func.exp: hi-cold: no-cold-names: x/2i foo_cold
FAIL: gdb.dwarf2/dw2-ranges-func.exp: hi-cold: no-cold-names: info line *foo_cold

gdb/testsuite/ChangeLog:

	* gdb.dwarf2/dw2-ranges-func.c: Rename to...
	* gdb.dwarf2/dw2-ranges-func-lo-cold.c: ...this.
	* gdb.dwarf2/dw2-ranges-func-lo-cold.c (foo_low): Change name to
	foo_cold.  Revise comments to match.
	* gdb.dwarf2/dw2-ranges-func-hi-cold.c: New file.
	* gdb.dwarf2/dw2-ranges-func.exp (do_test): New proc. Existing tests
	were wrapped into this proc; Call do_test in loop from outermost
	level.
	(foo_low): Rename all occurrences to "foo_cold".
	(backtrace from baz): New test.
	(x2/i foo_cold): New test.
	(info line *foo_cold): New test.