src/ast_render.cpp: fix rendering of character literals <= 0x0f
src/ast_render.cpp: fix rendering of character literals <= 0x0f

raulgrell/zig,andrewrk/zig,raulgrell/zig,zig-lang/zig,zig-lang/zig,zig-lang/zig,andrewrk/zig,raulgrell/zig,raulgrell/zig,raulgrell/zig