Fix Linux bug that leaves lldb in invalid state after expression evaluation times out.
- Handle EINVAL return code from ptrace(GETSIGINFO, ...): not an error, but 'group-stop' state on Linux
- propagate SIGSTOP to inferior in above case
- this commit resolves the failure in expression_command/timeout testcase

Thanks to Sean Callanan & Matt Kopec for helping debug this problem

llvm-svn: 168523
diff --git a/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.h b/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.h
index 9c63004..5530ca3 100644
--- a/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.h
+++ b/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.h
@@ -132,7 +132,7 @@
     /// Writes a siginfo_t structure corresponding to the given thread ID to the
     /// memory region pointed to by @p siginfo.
     bool
-    GetSignalInfo(lldb::tid_t tid, void *siginfo);
+    GetSignalInfo(lldb::tid_t tid, void *siginfo, int &errno);
 
     /// Writes the raw event message code (vis-a-vis PTRACE_GETEVENTMSG)
     /// corresponding to the given thread IDto the memory pointed to by @p