Changed test

On arm, we start in a different place than _start (some
assembly, possibly handrolled), which made setting a breakpoint at 48
wrong, so had to put the filename:line number.

Tests should pass now.

Author: theIDinside

src/test/checkpoint_persistent_shmem.py

@@ -1,6 +1,6 @@
 from util import *
 
-send_gdb('break 48')
+send_gdb('break checkpoint_persistent_shmem.c:48')
 expect_gdb('Breakpoint 1')
 send_gdb('c')
 expect_gdb('Breakpoint 1')
@@ -19,4 +19,4 @@
 send_gdb('print ptr')
 expect_gdb('"hello parenthello child"')
 
-ok()
+ok()