debuggerd: Fix minor memory leak

free_ptrace_context(context) doesn't free(context),
which leaks the memory allocated to context.

Change-Id: Ic199b257aefc9a05ec2d902958efa8a57a601fb1
Signed-off-by: Liangtao Gao <gliangtao@gmail.com>
Merge "debuggerd: Fix minor memory leak" into jb42