[build] Use cheap-ruler-cpp provided via mapbox-base

.gitmodules

@@ -34,9 +34,6 @@
 [submodule "vendor/benchmark"]
 	path = vendor/benchmark
 	url = https://github.com/google/benchmark.git
-[submodule "vendor/cheap-ruler-cpp"]
-	path = vendor/cheap-ruler-cpp
-	url = https://github.com/mapbox/cheap-ruler-cpp.git
 [submodule "vendor/glfw"]
 	path = vendor/glfw
 	url = https://github.com/glfw/glfw.git

platform/glfw/CMakeLists.txt

@@ -28,8 +28,6 @@ target_include_directories(
     PRIVATE ${PROJECT_SOURCE_DIR}/src
 )
 
-include(${PROJECT_SOURCE_DIR}/vendor/cheap-ruler-cpp.cmake)
-
 # Use target_link_directories when we move away from CMake 3.10.
 target_link_libraries(
     mbgl-glfw
@@ -45,7 +43,7 @@ target_link_libraries(
         Mapbox::Base::Extras::rapidjson
         Mapbox::Map
         mbgl-compiler-options
-        mbgl-vendor-cheap-ruler-cpp
+        Mapbox::Base::cheap-ruler-cpp
 )
 
 if(MBGL_WITH_OPENGL)

vendor/cheap-ruler-cpp.cmake

@@ -1,12 +0,0 @@
-if(TARGET mbgl-vendor-cheap-ruler-cpp)
-    return()
-endif()
-
-add_library(
-    mbgl-vendor-cheap-ruler-cpp INTERFACE
-)
-
-target_include_directories(
-    mbgl-vendor-cheap-ruler-cpp SYSTEM
-    INTERFACE ${CMAKE_CURRENT_LIST_DIR}/cheap-ruler-cpp/include
-)