[compiler-rt][asan] Disable two tests on Arm Thumb

I can't be sure of the cause but I believe these fail
due to to fast unwinding not working on Thumb.

Whatever the case, they have been failing on our bots
for a long time:
https://lab.llvm.org/buildbot/#/builders/170/builds/46

Require fast-unwinder-works for both.

compiler-rt/test/asan/TestCases/Linux/odr-violation.cpp

@@ -43,6 +43,8 @@
 // GNU driver doesn't handle .so files properly.
 // REQUIRES: Clang
 
+// REQUIRES: fast-unwinder-works
+
 #ifndef SZ
 # define SZ 4
 #endif

compiler-rt/test/asan/TestCases/Linux/recvfrom.cpp

@@ -4,7 +4,8 @@
 // RUN: %clangxx_asan %s -DSENDTO -o %t && not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-SENDTO
 // RUN: %clangxx_asan %s -DSENDTO -o %t && %env_asan_opts=intercept_send=0 %run %t 2>&1
 //
-// UNSUPPORTED: android
+// This will try to fast unwind on Arm Thumb, where fast unwinding does not work.
+// UNSUPPORTED: android, !fast-unwinder-works
 
 #include <stdio.h>
 #include <unistd.h>