[mips][asan] Fix preinstalled_signal.cc test for mips

Linux for mips has a non-standard layout for the kernel sigaction struct.
Adjust the layout by the minimally amount to get the test to pass, as we
don't require the usage of the restorer function.

llvm-svn: 314200

compiler-rt/test/asan/TestCases/Linux/preinstalled_signal.cc

@@ -32,8 +32,14 @@ void SigHandler(int signum) { handler = "TestSigHandler"; }
 void SigAction(int, siginfo_t *, void *) { handler = "TestSigAction"; }
 
 struct KernelSigaction {
+
+#if defined(__mips__)
+  unsigned long flags;
+  __sighandler_t handler;
+#else
   __sighandler_t handler;
   unsigned long flags;
+#endif
   void (*restorer)();
   char unused[1024];
 };