[LLGS] Log more precise errors during inferior launch

Summary:
We are seeing infrequent failures to launch the inferior process on android. The failing call
seems to be execve(). This adds more logging to see the actual error reported by the call.

Reviewers: tberghammer

Subscribers: tberghammer, lldb-commits, danalbert

Differential Revision: http://reviews.llvm.org/D22039

llvm-svn: 274624
diff --git a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.h b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.h
index c335f86..d00b9c8 100644
--- a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.h
+++ b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.h
@@ -202,6 +202,9 @@
         ::pid_t
         Attach(lldb::pid_t pid, Error &error);
 
+        static void
+        ChildFunc(const LaunchArgs &args) LLVM_ATTRIBUTE_NORETURN;
+
         static Error
         SetDefaultPtraceOpts(const lldb::pid_t);