Use docker_image for musl

Author: zanieb

cpython-unix/Makefile

@@ -86,7 +86,7 @@ $(OUTDIR)/$(CLANG_FILENAME):
 	$(RUN_BUILD) --toolchain clang --target-triple $(TARGET_TRIPLE)
 
 $(OUTDIR)/musl-$(MUSL_VERSION)-$(HOST_PLATFORM).tar: $(BASE_TOOLCHAIN_DEPENDS) $(HERE)/build-musl.sh
-	$(RUN_BUILD) --toolchain musl
+	$(RUN_BUILD) --toolchain musl --docker-image $(DOCKER_IMAGE_GCC)
 
 ifeq ($(HOST_PLATFORM),linux_x86_64)
     TOOLCHAIN_TARGET := $(OUTDIR)/musl-$(MUSL_VERSION)-$(HOST_PLATFORM).tar

cpython-unix/build.py

@@ -1110,7 +1110,7 @@ def main():
         elif action == "musl":
             build_musl(
                 client,
-                get_image(client, ROOT, BUILD, "gcc", host_platform),
+                get_image(client, ROOT, BUILD, docker_image, host_platform),
                 host_platform,
                 target_triple,
                 build_options,