Fix for building ARM/linux using clang.

src/trusted/service_runtime/nacl_syscall_common.c

 /*
  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /*
  * NaCl service run-time, non-platform specific system call helper routines.
  */
 #include <sys/types.h>
@@ skipping 873 matching lines @@
 #elif NACL_ARCH(NACL_BUILD_ARCH) == NACL_arm
   /*
    * Put some interesting bits into the VFP registers.
    */
 
   static const char manybytes[64] =
       "Sensitive information must not be leaked to untrusted code!!!!\n";
 
   __asm__ volatile("vldm %0, {d0-d7}" :: "r" (manybytes) :
                    "d0", "d1", "d2", "d3", "d4", "d5", "d6", "d7");
+
+  /*
+   * __builtin_arm_set_fpscr is not available yet in gcc (not even in 4.8)
+   * and clang doesn't know about the "vfpcc" register.
+   * TODO(sbc): Always use __builtin_arm_set_fpscr once we are using a
+   * version of gcc that supports it.
+   */
+#ifdef __clang__
+  __builtin_arm_set_fpscr(0xdeadbeef);
+#else
   __asm__ volatile("fmxr fpscr, %0" :: "r" (0xdeadbeef) : "vfpcc");
+#endif
 
 #elif NACL_ARCH(NACL_BUILD_ARCH) == NACL_mips
 
   static const char manybytes[128] =
       "Sensitive information must not be leaked to untrusted code!!!\n"
       "Where is Maletoth?\n";
 
   __asm__ volatile("ldc1  $f0,  0(%0)\n"
                    "ldc1  $f2,  8(%0)\n"
                    "ldc1  $f4,  16(%0)\n"
@@ skipping 137 matching lines @@
   return NaClSysClockGetCommon(natp, clk_id, (uintptr_t) tsp,
                                NaClClockGetRes, 1);
 }
 
 int32_t NaClSysClockGetTime(struct NaClAppThread  *natp,
                             int                   clk_id,
                             uint32_t              tsp) {
   return NaClSysClockGetCommon(natp, clk_id, (uintptr_t) tsp,
                                NaClClockGetTime, 0);
 }