Basic compilation on Fuchsia

Sufficient to compile //v8 in Chrome with target_os="fuchsia". Doesn't
link yet, due to missing implementations (primarily VirtualMemory, as
well as a few utility functions).

BUG=chromium:731217
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_chromium_rel_ng

Review-Url: https://codereview.chromium.org/2931143002
Cr-Commit-Position: refs/heads/master@{#45831}

include/v8config.h

@@ -61,6 +61,7 @@
 //  V8_OS_CYGWIN        - Cygwin
 //  V8_OS_DRAGONFLYBSD  - DragonFlyBSD
 //  V8_OS_FREEBSD       - FreeBSD
+//  V8_OS_FUCHSIA       - Fuchsia
 //  V8_OS_LINUX         - Linux
 //  V8_OS_MACOSX        - Mac OS X
 //  V8_OS_NETBSD        - NetBSD
@@ -95,6 +96,9 @@
 # define V8_OS_BSD 1
 # define V8_OS_FREEBSD 1
 # define V8_OS_POSIX 1
+#elif defined(__Fuchsia__)
+# define V8_OS_FUCHSIA 1
+# define V8_OS_POSIX 1
 #elif defined(__DragonFly__)
 # define V8_OS_BSD 1
 # define V8_OS_DRAGONFLYBSD 1

src/base/platform/platform-posix.cc

@@ -362,6 +362,8 @@ int OS::GetCurrentThreadId() {
   return static_cast<int>(gettid());
 #elif V8_OS_AIX
   return static_cast<int>(thread_self());
+#elif V8_OS_FUCHSIA
+  return static_cast<int>(pthread_self());
 #elif V8_OS_SOLARIS
   return static_cast<int>(pthread_self());
 #else

src/libsampler/sampler.cc

@@ -415,7 +415,7 @@ void SignalHandler::FillRegisterState(void* context, RegisterState* state) {
 #if !(V8_OS_OPENBSD || (V8_OS_LINUX && (V8_HOST_ARCH_PPC || V8_HOST_ARCH_S390)))
   mcontext_t& mcontext = ucontext->uc_mcontext;
 #endif
-#if V8_OS_LINUX
+#if V8_OS_LINUX || V8_OS_FUCHSIA
 #if V8_HOST_ARCH_IA32
   state->pc = reinterpret_cast<void*>(mcontext.gregs[REG_EIP]);
   state->sp = reinterpret_cast<void*>(mcontext.gregs[REG_ESP]);