Make 'run-until-faulted.py' script more interesting by modifying the example main.c program

to seg fault randomly instead of deterministically.

Example:

[15:10:43] johnny:/Volumes/data/lldb/svn/trunk/utils/test $ clang -g main.c
[15:10:46] johnny:/Volumes/data/lldb/svn/trunk/utils/test $ ./run-until-faulted.py -l $PWD/../../build/Debug/lldb -e a.out
lldb command: /Volumes/data/lldb/svn/trunk/utils/test/../../build/Debug/lldb
executable: a.out
executable options: 
(lldb) sending 'file a.out' command...
file a.out
Current executable set to 'a.out' (x86_64).
(lldb) sending 'process launch -- ' command... (iteration: 0)
process launch -- 
Process 63630 launched: '/Volumes/data/lldb/svn/trunk/utils/test/a.out' (x86_64)
Hello, fault!
val=9
Better luck next time!
[KProcess 63630 exited with status = 0 (0x00000000) 
(lldb) sending 'process launch -- ' command... (iteration: 1)
process launch -- 
Process 63633 launched: '/Volumes/data/lldb/svn/trunk/utils/test/a.out' (x86_64)
[KProcess 63633 exited with status = 0 (0x00000000) 
sending 'process launch -- ' command... (iteration: 2)
[KHello, fault!
val=0
Better luck next time!
(lldb) process launch -- 
Process 63637 launched: '/Volumes/data/lldb/svn/trunk/utils/test/a.out' (x86_64)
Hello, fault!
val=15
Better luck next time!
[KProcess 63637 exited with status = 0 (0x00000000) 
(lldb) sending 'process launch -- ' command... (iteration: 3)
process launch -- 
Process 63640 launched: '/Volumes/data/lldb/svn/trunk/utils/test/a.out' (x86_64)
Hello, fault!
val=2
Better luck next time!
[KProcess 63640 exited with status = 0 (0x00000000) 
sending 'process launch -- ' command... (iteration: 4)
(lldb) process launch -- 
Process 63643 launched: '/Volumes/data/lldb/svn/trunk/utils/test/a.out' (x86_64)
[KProcess 63643 stopped
* thread #1: tid = 0x2d03, 0x0000000100000e93 a.out`main + 99 at main.c:11, stop reason = EXC_BAD_ACCESS (code=1, address=0x0)
  frame #0: 0x0000000100000e93 a.out`main + 99 at main.c:11
   8   	    u_int32_t val = (arc4random() & 0x0f);
   9   	    printf("val=%u\n", val);
   10  	    if (val == 0x07) // Lucky 7 :-)
-> 11  	        printf("Now segfault %d\n", *null_ptr);
   12  	    else
   13  	        printf("Better luck next time!\n");
   14  	}
(lldb) 
* thread #1: tid = 0x2d03, 0x0000000100000e93 a.out`main + 99 at main.c:11, stop reason = EXC_BAD_ACCESS (code=1, address=0x0)
  frame #0: 0x0000000100000e93 a.out`main + 99 at main.c:11
   8   	    u_int32_t val = (arc4random() & 0x0f);
   9   	    printf("val=%u\n", val);
   10  	    if (val == 0x07) // Lucky 7 :-)
-> 11  	        printf("Now segfault %d\n", *null_ptr);
   12  	    else
   13  	        printf("Better luck next time!\n");
   14  	}
[KHello, fault!
val=7
(lldb) 

llvm-svn: 132430