Fix fail in gdb.mi/mi-reverse.exp
    
    Commit 38b022b4452f996fb5a8598f80d850b594621bcf adds "method" and
    "format" fields in =record-started, but doesn't update test case
    gdb.mi/mi-reverse.exp, so it causes the fail like this,
    
    PASS: gdb.mi/mi-reverse.exp: mi runto main
    Expecting: ^(-interpreter-exec console record[^M
    ]+)?(=record-started,thread-group="i1"^M
    \^done[^M
    ]+[(]gdb[)] ^M
    [ ]*)
    -interpreter-exec console record^M
    =record-started,thread-group="i1",method="full"^M
    ^done^M
    (gdb) ^M
    FAIL: gdb.mi/mi-reverse.exp: Turn on process record
    
    and regression was found by buildbot too
    https://sourceware.org/ml/gdb-testers/2016-q2/msg04492.html
    
    gdb/testsuite:
    
    2016-07-05  Yao Qi  <yao.qi@linaro.org>
    
    	* gdb.mi/mi-reverse.exp: Match =record-started output.