fixup -Werror=missing-declarations

src/CMakeLists.txt

@@ -136,6 +136,10 @@ else()
         -Wno-unused-parameter
         -Wno-missing-field-initializers
     )
+    # iOS clang doesn't like this specific option
+    if (NOT IOS)
+        add_compile_options(-Werror=missing-declarations)
+    endif()
 
     if (CXX_CLANG OR CXX_ICC OR CXX_APPLE) # Clang, AppleClang, or Intel C++
         if (NOT MSVC)