[build] Use a submodule for mapbox-gl-js rather than an npm dependency

.gitmodules

@@ -12,3 +12,6 @@
 [submodule "platform/ios/uitest/OHHTTPStubs"]
 	path = platform/ios/uitest/OHHTTPStubs
 	url = https://github.com/AliSoftware/OHHTTPStubs.git
+[submodule "mapbox-gl-js"]
+	path = mapbox-gl-js
+	url = git://github.com/mapbox/mapbox-gl-js.git

CMakeLists.txt

@@ -10,6 +10,12 @@ if(NOT EXISTS ".mason/mason.cmake")
         WORKING_DIRECTORY ${CMAKE_SOURCE_DIR})
 endif()
 
+if(NOT EXISTS "mapbox-gl-js/package.json")
+   execute_process(
+        COMMAND git submodule update --init mapbox-gl-js
+        WORKING_DIRECTORY ${CMAKE_SOURCE_DIR})
+endif()
+
 include(.mason/mason.cmake)
 
 option(WITH_CXX11ABI "Use cxx11abi mason packages" OFF)

cmake/shaders.cmake

@@ -1,6 +1,6 @@
 function(add_shader VAR name)
     set(shader_build_cmd ${NodeJS_EXECUTABLE} ${CMAKE_SOURCE_DIR}/scripts/build-shaders.js)
-    set(shader_file_prefix ${CMAKE_SOURCE_DIR}/node_modules/mapbox-gl/shaders)
+    set(shader_file_prefix ${CMAKE_SOURCE_DIR}/mapbox-gl-js/shaders)
     set(shader_source_prefix ${MBGL_GENERATED}/include/mbgl/shader)
 
     add_custom_command(

package.json

@@ -22,7 +22,6 @@
     "ejs": "^2.4.1",
     "express": "^4.11.1",
     "lodash": "^4.16.4",
-    "mapbox-gl": "mapbox/mapbox-gl-js#ef5582dd3bc5c15a3112e875ed66494dab8e9d0b",
     "mapbox-gl-style-spec": "mapbox/mapbox-gl-style-spec#49e8b407bdbbe6f7c92dbcb56d3d51f425fc2653",
     "mapbox-gl-test-suite": "mapbox/mapbox-gl-test-suite#da53a81453068f4c2b440f9077d6bd5e7e14ff3d",
     "mkdirp": "^0.5.1",