[gn] Add cctest

BUG=chromium:474921

Committed: https://crrev.com/52a6fced896e3f64ac56eb57bcdea78393642e0c
Cr-Commit-Position: refs/heads/master@{#36517}

Committed: https://crrev.com/65678bc67fc48dfe4dcab7fdd2c4b7e1d6e918f4
Cr-Commit-Position: refs/heads/master@{#36586}

TBR=jochen@chromium.org

Review-Url: https://codereview.chromium.org/2007143003
Cr-Commit-Position: refs/heads/master@{#36607}

BUILD.gn

@@ -2070,6 +2070,7 @@ group("gn_all") {
   if (host_os != "mac" || !is_android) {
     # These items don't compile for Android on Mac.
     deps += [
+      "test/cctest:cctest",
       "test/unittests:unittests",
     ]
   }

test/cctest/test-platform.cc

@@ -17,7 +17,7 @@ void GetStackPointer(const v8::FunctionCallbackInfo<v8::Value>& args) {
 #elif V8_HOST_ARCH_IA32
   __asm__ __volatile__("mov %%esp, %0" : "=g"(sp_addr));
 #elif V8_HOST_ARCH_ARM
-  __asm__ __volatile__("str %%sp, %0" : "=g"(sp_addr));
+  __asm__ __volatile__("str sp, %0" : "=g"(sp_addr));
 #elif V8_HOST_ARCH_ARM64
   __asm__ __volatile__("mov x16, sp; str x16, %0" : "=g"(sp_addr));
 #elif V8_HOST_ARCH_MIPS