Support rustup override

Author: SimonSapin

rebuild-libcore.sh

@@ -6,7 +6,7 @@ SRC_DIR=$SYSROOT/lib/rustlib/src/rust/src/libcore
 LIB_DIR=$SYSROOT/lib/rustlib/$TARGET/lib
 
 cp $(dirname $0)/$TARGET.json $SRC_DIR
-cd $SRC_DIR
-cargo rustc --release --target=$TARGET -- -C panic=abort
+# Don’t cd into $SRC_DIR, use current directory’s rustup override.
+cargo rustc --manifest-path $SRC_DIR/Cargo.toml --release --target=$TARGET -- -C panic=abort
 mkdir -p $LIB_DIR
-cp target/$TARGET/release/libcore.rlib $LIB_DIR
+cp $SRC_DIR/target/$TARGET/release/libcore.rlib $LIB_DIR