const conversion in String::erase

[MrMinimal]

I just tried the latest master at 83cc9b8
with the latest godot_headers at 23872837e77e39ba6ab21393f26e531d1ae0a7b6

Compiling the project with both clang and g++ on Ubuntu 16.04 yields the following problem:

: In member function 'void godot::String::erase(int, int) const':
src/core/String.cpp:157:21: error: invalid conversion from 'const godot_string*' to 'godot_string*' [-fpermissive]
  godot_string_erase(&_godot_string, position, chars);
                     ^~~~~~~~~~~~~~
In file included from include/core/String.hpp:4:0,
                 from src/core/String.cpp:1:
/home/mrminimal/Dev/SimpleLibrary/godot_headers/gdnative/string.h:167:12: note:   initializing argument 1 of 'void godot_string_erase(godot_string*, godot_int, godot_int)'
 void GDAPI godot_string_erase(godot_string *p_self, godot_int p_pos, godot_int p_chars);
            ^~~~~~~~~~~~~~~~~~

Any idea on how to fix it? Is it a preprocessor thing?