Tests: check for target availability for target-specific tests.

Lots of tests are using an explicit target triple w/o first checking that the
target is actually available. Add a REQUIRES clause to a bunch of them. This should
hopefully unbreak bots which don't configure w/ all targets enabled.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@159949 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/arm-vector-align.c b/test/CodeGen/arm-vector-align.c
index b481a0c..9e1ae5d 100644
--- a/test/CodeGen/arm-vector-align.c
+++ b/test/CodeGen/arm-vector-align.c
@@ -1,3 +1,4 @@
+// REQUIRES: arm-registered-target
 // RUN: %clang_cc1 -triple thumbv7-apple-darwin \
 // RUN:   -target-abi apcs-gnu \
 // RUN:   -target-cpu cortex-a8 \