For all RUN lines starting with "not", redirect stderr to /dev/null so tests

don't fail when (expected) error output is produced. This fixes 17 tests.

While I was there, I also made all RUN lines of the form "not llvm-as..." a bit
more consistent, they now all redirect stderr and stdout to /dev/null and use
input redirect to read their input.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52174 91177308-0d34-0410-b5e6-96231b3b80d8

test/Verifier/gcroot-alloca.ll

@@ -1,4 +1,4 @@
-; RUN: not llvm-as < %s
+; RUN: not llvm-as < %s >& /dev/null
 ; PR1633
 
 %meta = type { i8* }