fix crosscompiler path

Dockerfile.rpi

@@ -14,8 +14,8 @@ COPY . .
 ENV PATH /depot_tools:$PATH
 
 RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends ca-certificates build-essential gcc wget git python3 python3-pkg-resources xz-utils cmake make pkg-config \
-    && wget -qO- ${CROSSCOMPILER} | tar xz -C /webrtc \
-	&& export PATH=$(ls -d /webrtc/cross-pi-gcc-*/bin):$PATH \
+    && wget -qO- ${CROSSCOMPILER} | tar xz -C /build \
+	&& export PATH=$(ls -d /build/cross-pi-gcc-*/bin):$PATH \
 	&& git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git /depot_tools \
 	&& mkdir ../webrtc \
 	&& cd ../webrtc \