Port linux_syscall_support and linux_dumper to support Linux ARM. Unit tests...

src/client/linux/handler/exception_handler.cc

Index: src/client/linux/handler/exception_handler.cc
===================================================================
--- src/client/linux/handler/exception_handler.cc	(revision 400)
+++ src/client/linux/handler/exception_handler.cc	(working copy)
@@ -87,7 +87,7 @@
 
 // A wrapper for the tgkill syscall: send a signal to a specific thread.
 static int tgkill(pid_t tgid, pid_t tid, int sig) {
-  syscall(__NR_tgkill, tgid, tid, sig);
+  return syscall(__NR_tgkill, tgid, tid, sig);
 }
 
 namespace google_breakpad {
@@ -171,6 +171,7 @@
       return false;
     old_handlers_.push_back(std::make_pair(kExceptionSignals[i], old));
   }
+  return true;
 }
 
 // Runs before crashing: normal context.
@@ -264,8 +265,11 @@
   CrashContext context;
   memcpy(&context.siginfo, info, sizeof(siginfo_t));
   memcpy(&context.context, uc, sizeof(struct ucontext));
+#if !defined(__ARM_ARCH_7A__)
+  // FP state is not part of user ABI on ARM Linux.
   memcpy(&context.float_state, ((struct ucontext *)uc)->uc_mcontext.fpregs,
          sizeof(context.float_state));
+#endif
   context.tid = sys_gettid();
 
   if (crash_handler_ && crash_handler_(&context, sizeof(context),