[ox] Improve hasing and MaybeView

* Add CityHash dep
* Use CityHash for HashMap
* Make MaybeView more versatile
* Cleanup some inappropriate MaybeView uses

(synced from 32e4702dc7)

deps/cityhash/CMakeLists.txt

@@ -0,0 +1,30 @@
+cmake_minimum_required(VERSION 3.19)
+set(CMAKE_POLICY_DEFAULT_CMP0110 NEW) # requires CMake 3.19
+
+project(CityHash CXX)
+
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+
+set(NOSTALGIA_BUILD_PLAYER OFF)
+set(NOSTALGIA_BUILD_STUDIO_APP OFF)
+
+set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
+set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
+set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
+
+if(APPLE)
+	set(CMAKE_MACOSX_RPATH OFF)
+else()
+	if(UNIX)
+		set(BUILD_SHARED_LIBS ON)
+	endif()
+	set(CMAKE_INSTALL_RPATH "$ORIGIN/../lib")
+	set(CMAKE_BUILD_WITH_INSTALL_RPATH TRUE)
+endif()
+
+add_library(CityHash INTERFACE)
+target_include_directories(CityHash INTERFACE include)