[patch/rfc] Rewrite "structs" testcase

[Michael Elizabeth Chastain]

I'm getting 508 PASS / 71 KFAIL with three configurations,
but I'm getting 504 PASS / 4 FAIL / 71 KFAIL with gcc 3.3.2 -gdwarf-2.

The FAILs are

  # gcc 3.3.2, binutils 2.14, -gdwarf-2

  p/c fun2()
  $1 = {a = 97 'a', b = 0 '\0'}
  (gdb) FAIL: gdb.base/structs.exp: p/c fun2(); call 2 structs-tc-tll

  p/c L2
  $2 = {a = 97 'a', b = 0 '\0'}
  (gdb) FAIL: gdb.base/structs.exp: p/c L2; call 2 structs-tc-tll

  p/c fun2()
  $1 = {a = 97 'a', b = 0 '\0'}
  (gdb) FAIL: gdb.base/structs.exp: p/c fun2(); call 2 structs-tc-td

  p/c L2
  $2 = {a = 97 'a', b = 0 '\0'}
  (gdb) FAIL: gdb.base/structs.exp: p/c L2; call 2 structs-tc-td

Do these look like bugs in the script or bugs in gdb?  If they are
bugs in gdb then the test script is doing a good job.

Michael C