Fix gdb.reverse/next-reverse-bkpt-over-sr.exp

Fix gdb.reverse/next-reverse-bkpt-over-sr.exp

I see the fail on aarch64-linux,

(gdb) reverse-next

Breakpoint 2, callee () at /home/yao/SourceCode/gnu/gdb/git/gdb/testsuite/gdb.reverse/step-reverse.c:26^M
26        myglob++; return 0;   /* ARRIVED IN CALLEE */
(gdb) FAIL: gdb.reverse/next-reverse-bkpt-over-sr.exp: reverse-next over call trips user breakpoint at function entry

The test expects program stops at line 25, but program stops at line 26.

(gdb) maintenance info line-table
objfile: /scratch/yao/gdb/build-git/aarch64-linux-gnu/gdb/testsuite/outputs/gdb.reverse/next-reverse-bkpt-over-sr/next-reverse-bkpt-over-sr ((struct objfile *) 0x613000002880)
compunit_symtab: ((struct compunit_symtab *) 0x621000121760)
symtab: /home/yao/SourceCode/gnu/gdb/git/gdb/testsuite/gdb.reverse/step-reverse.c ((struct symtab *) 0x6210001217e0)
linetable: ((struct linetable *) 0x6210001520d0):
INDEX    LINE ADDRESS
0          25 0x0000000000400890
1          26 0x0000000000400890
2          27 0x00000000004008b0

(gdb) disassemble callee
Dump of assembler code for function callee:
   0x0000000000400890 <+0>:     adrp    x0, 0x410000
   0x0000000000400894 <+4>:     add     x0, x0, #0xcac

the line-table show that the first instruction of function callee is
mapped line 25 and 26.  I am not sure the line-table is correct, but
it is not the point of this test.  The goal of this test is to test
program hits the breakpoint on the first instruction of function after
'reverse-next', so I change this test to expect the breakpoint number
the program hits.

gdb/testsuite:

2016-04-07  Yao Qi  <yao.qi@linaro.org>

	* gdb.reverse/next-reverse-bkpt-over-sr.exp: Match the breakpoint
	number instead of the comments on some line.