[compiler-rt][hwasan][Fuchsia] Do not emit FindDynamicShadowStart for Fuchsia

[leonardchan]

Summary

This function is unused because fuchsia does not support a dynamic shadow.

[mcgrathr]

I think it would be more in keeping with local style to make this a third #elif SANITIZER_FUCHSIA leg in the middle with the InitShadowGOT stub. FindDynamicShadowStart is only called from Linux-specific code and does not need to be defined.

[leonardchan]

In D105735#2888311, @mcgrathr wrote:

I think it would be more in keeping with local style to make this a third #elif SANITIZER_FUCHSIA leg in the middle with the InitShadowGOT stub. FindDynamicShadowStart is only called from Linux-specific code and does not need to be defined.

Something like this?

[mcgrathr]

lgtm

compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp

116

Put blank lines around #if et al.

compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp

 uptr FindDynamicShadowStart(uptr shadow_size_bytes) {
   if (IsPremapShadowAvailable())
     return FindPremappedShadowStart(shadow_size_bytes);
   return MapDynamicShadow(shadow_size_bytes, kShadowScale, kShadowBaseAlignment,
                           kHighMemEnd);
 }
 
 }  // namespace __hwasan
+#elif SANITIZER_FUCHSIA
+namespace __hwasan {
+
+void InitShadowGOT() {}
+
+}  // namespace __hwasan
 #else
 namespace __hwasan {
 
 void InitShadowGOT() {}
 
 uptr FindDynamicShadowStart(uptr shadow_size_bytes) {
 #  if defined(HWASAN_ALIASING_MODE)
   constexpr uptr kAliasSize = 1ULL << kAddressTagShift;