Fix to build with C++ environment

C++ requires additional runtime to be linked by rust linker.

Reference:
rust-lang/rust#36710 (comment)

.cargo/config

@@ -1,3 +1,2 @@
 [target.x86_64-unknown-linux-musl]
-linker = "/opt/cross/bin/x86_64-linux-musl-gcc"
-rustflags = ["-C", "link-args=-static"]
+linker = "./linker"

Makefile

@@ -11,4 +11,4 @@ rust:
 
 .PHONY: rust-musl
 rust-musl:
-	CXX=/opt/cross/bin/x86_64-linux-musl-g++ cargo run --target x86_64-unknown-linux-musl
+	CROSS_COMPILE=/opt/cross/bin/x86_64-linux-musl- cargo run --target x86_64-unknown-linux-musl

linker

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+args=()
+
+for arg in "$@"; do
+	if [[ $arg = *"Bdynamic"* ]]; then
+		args+=() # we do not want this arg
+	elif [[ $arg = *"crti.o"* ]]; then
+		args+=("$arg" "/opt/cross/lib/gcc/x86_64-linux-musl/9.2.0/crtbeginS.o" "-Bstatic")
+	elif [[ $arg = *"crtn.o"* ]]; then
+		args+=("-lgcc" "-lgcc_eh" "-lc" "/opt/cross/lib/gcc/x86_64-linux-musl/9.2.0/crtendS.o" "$arg")
+	else
+		args+=("$arg")
+	fi
+done
+
+echo "RUNNING WITH ARGS: ${args[@]}"
+/opt/cross/bin/x86_64-linux-musl-g++ "${args[@]}"