[Fix]: fix glmark2 crash

- deal with legacy GLSL syntax (attribute/varying/gl_FragColor/texture2D/etc.)
- implement glGet GL_SHADER_SOURCE_LENGTH, and make sure returns
  original shader source
- expose proper extensions (GL_ARB_depth_texture)
- support env var MOBILEGL_LOG_FILE_PATH
- unit tests to test against those changes

MobileGL/MG_Test/CMakeLists.txt

@@ -35,6 +35,12 @@ add_executable(
 target_link_libraries(
   SanityTest
   GTest::gtest_main
+  MobileGL_s
+)
+
+target_include_directories(SanityTest PRIVATE
+  ${MGL_ROOT}/include
+  ${MGL_ROOT}/MobileGL
 )
 
 # message(STATUS "glslang_LIBRARIES: ${glslang_LIBRARIES}")
@@ -63,4 +69,4 @@ add_subdirectory(VertexArray)
 add_subdirectory(Program)
 if (ENABLE_INTEGRATION_TESTS)
     add_subdirectory(Backend/DirectVulkan)
-endif()
+endif()