testsuite: Regression for foll-vfork.exp

testsuite: Regression for foll-vfork.exp

fe33faff35a8ee19db823149e764e3373e603bb9 is the first bad commit
commit fe33faff35a8ee19db823149e764e3373e603bb9
Author: Simon Marchi <simon.marchi@ericsson.com>
Date:   Tue Dec 22 10:52:31 2015 -0500
    Remove HP-UX reference in foll-vfork.exp

FAIL: gdb.base/foll-vfork.exp: exec: vfork parent follow, finish after tcatch vfork: continue to vfork
FAIL: gdb.base/foll-vfork.exp: exec: vfork child follow, finish after tcatch vfork: continue to vfork
FAIL: gdb.base/foll-vfork.exp: exit: vfork parent follow, finish after tcatch vfork: continue to vfork
FAIL: gdb.base/foll-vfork.exp: exit: vfork child follow, finish after tcatch vfork: continue to vfork

It happens for plain gdb.base/foll-vfork.exp runtest on Fedora 23 x86_64.

-Temporary catchpoint 2 (vforked process 24562), vfork () at ../sysdeps/unix/sysv/linux/x86_64/vfork.S:52^M
+Temporary catchpoint 2 (vforked process 25345), vfork () at ../sysdeps/unix/sysv/linux/x86_64/vfork.S:52^M
 52             pushq   %rdi^M
 Current language:  auto^M
 The current source language is "auto; currently asm".^M
-(gdb) PASS: gdb.base/foll-vfork.exp: exec: vfork parent follow, finish after tcatch vfork: continue to vfork
+(gdb) FAIL: gdb.base/foll-vfork.exp: exec: vfork parent follow, finish after tcatch vfork: continue to vfork

-Temporary catchpoint 2 (vforked process 24629), vfork () at ../sysdeps/unix/sysv/linux/x86_64/vfork.S:52^M
+Temporary catchpoint 2 (vforked process 25411), vfork () at ../sysdeps/unix/sysv/linux/x86_64/vfork.S:52^M
 52             pushq   %rdi^M
 Current language:  auto^M
 The current source language is "auto; currently asm".^M
-(gdb) PASS: gdb.base/foll-vfork.exp: exec: vfork child follow, finish after tcatch vfork: continue to vfork
+(gdb) FAIL: gdb.base/foll-vfork.exp: exec: vfork child follow, finish after tcatch vfork: continue to vfork

So I have reverted it and just simplified the comment.

The third case is not necessary during testing but I have changed back all the
3 cases.

Pedro Alves:
I know it was that way before, but would you mind moving this to a helper
proc.

gdb/testsuite/ChangeLog
2016-01-11  Jan Kratochvil  <jan.kratochvil@redhat.com>
	    Pedro Alves  <palves@redhat.com>

	* gdb.base/foll-vfork.exp (tcatch_vfork_then_parent_follow)
	(tcatch_vfork_then_child_follow_exec)
	(tcatch_vfork_then_child_follow_exit): Revert back DWARF vfork
	identification.