Fix caching and set home to /user

Test Plan: Ran build

X-Origin-Diff: phab/D220
GitOrigin-RevId: d93c13b9a74c45d717e92151cdb10f0f3484a78b
diff --git a/build/utils/BUILD b/build/utils/BUILD
index d1abdd4..216ffff 100644
--- a/build/utils/BUILD
+++ b/build/utils/BUILD
@@ -77,7 +77,7 @@
         make configure
         ./configure CC="$$MUSL/bin/musl-gcc" CFLAGS="-static" --prefix=$$MUSL
         echo COMPILERING
-        make mkfs
+        make mkfs -j8
     ) > /dev/null
 
     cp external/xfsprogs_dev/mkfs/mkfs.xfs $(RULEDIR)