docker: add picolibc-include directory

Dockerfile

@@ -16,6 +16,7 @@ RUN cd /tinygo/ && \
     git submodule update --init --recursive --force
 
 COPY ./lib/picolibc-* /tinygo/lib/
+COPY ./lib/picolibc-include/* /tinygo/lib/picolibc-include/
 
 RUN cd /tinygo/ && \
     go install /tinygo/