Gcc 6 reports a warning on narrowing conversions. Turn this warning
off, and don't build with -Werror as it fails for some other reasons.

Upstream is not interested in this patch because they work on a
reimplementation of the game engine. Maintaining this one is not in
their top priorities.

---
 src/debug_console.cpp |    2 +-
 src/dialog.cpp        |    4 ++--
 src/texture.hpp       |    2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

--- a/src/texture.hpp
+++ b/src/texture.hpp
@@ -58,7 +58,7 @@
 	unsigned int get_id() const;
 	static void set_current_texture(unsigned int id);
 	void set_as_current_texture() const;
-	bool valid() const { return id_; }
+	bool valid() const { return (bool) id_; }
 
 	static texture get(const std::string& str, int options=0);
 	static texture get(const std::string& str, const std::string& algorithm);
--- a/Makefile
+++ b/Makefile
@@ -34,7 +34,7 @@
 endif
 
 # Initial compiler options, used before CXXFLAGS and CPPFLAGS.
-BASE_CXXFLAGS += -g -fno-inline-functions -fthreadsafe-statics -Wnon-virtual-dtor -Werror -Wignored-qualifiers -Wformat -Wswitch
+BASE_CXXFLAGS += -g -fno-inline-functions -fthreadsafe-statics -Wnon-virtual-dtor -Wignored-qualifiers -Wformat -Wswitch -Wno-narrowing
 
 # Compiler include options, used after CXXFLAGS and CPPFLAGS.
 INC := $(shell pkg-config --cflags x11 sdl glu glew SDL_image libpng zlib)
