Rename TARGET_OS_* to HOST_OS_*.

runtime/vm/profiler.cc

Index: runtime/vm/profiler.cc
diff --git a/runtime/vm/profiler.cc b/runtime/vm/profiler.cc
index 7110d082ae276e80ebd9b09549448502da39d0ee..ca72be792f70fac3d49398d05bc11495e1633ee8 100644
--- a/runtime/vm/profiler.cc
+++ b/runtime/vm/profiler.cc
@@ -31,7 +31,7 @@ static const intptr_t kMaxSamplesPerTick = 4;
 
 DEFINE_FLAG(bool, trace_profiled_isolates, false, "Trace profiled isolates.");
 
-#if defined(TARGET_OS_ANDROID) || defined(TARGET_ARCH_ARM64) ||                \
+#if defined(HOST_OS_ANDROID) || defined(TARGET_ARCH_ARM64) ||                  \
     defined(TARGET_ARCH_ARM) || defined(TARGET_ARCH_MIPS)
 DEFINE_FLAG(int,
             profile_period,
@@ -734,7 +734,7 @@ static void CopyStackBuffer(Sample* sample, uword sp_addr) {
 }
 
 
-#if defined(TARGET_OS_WINDOWS)
+#if defined(HOST_OS_WINDOWS)
 // On Windows this code is synchronously executed from the thread interrupter
 // thread. This means we can safely have a static fault_address.
 static uword fault_address = 0;
@@ -763,7 +763,7 @@ static void CollectSample(Isolate* isolate,
                           uword sp,
                           ProfilerCounters* counters) {
   ASSERT(counters != NULL);
-#if defined(TARGET_OS_WINDOWS)
+#if defined(HOST_OS_WINDOWS)
   // Use structured exception handling to trap guard page access on Windows.
   __try {
 #endif
@@ -791,7 +791,7 @@ static void CollectSample(Isolate* isolate,
       sample->SetAt(0, pc);
     }
 
-#if defined(TARGET_OS_WINDOWS)
+#if defined(HOST_OS_WINDOWS)
     // Use structured exception handling to trap guard page access.
   } __except (GuardPageExceptionFilter(GetExceptionInformation())) {  // NOLINT
     // Sample collection triggered a guard page fault:
@@ -961,7 +961,7 @@ static bool CheckIsolate(Isolate* isolate) {
 
 
 void Profiler::DumpStackTrace(void* context) {
-#if defined(TARGET_OS_LINUX) || defined(TARGET_OS_MACOS)
+#if defined(HOST_OS_LINUX) || defined(HOST_OS_MACOS)
   ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(context);
   mcontext_t mcontext = ucontext->uc_mcontext;
   uword pc = SignalHandler::GetProgramCounter(mcontext);