Add userspace ARM support

arm-unknown-redox.json

@@ -0,0 +1,26 @@
+{
+    "llvm-target": "arm-unknown-redox",
+    "target-endian": "little",
+    "target-pointer-width": "32",
+    "data-layout": "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64",
+    "arch": "arm",
+    "os": "redox",
+    "env": "",
+    "vendor": "unknown",
+    "target-family": "redox",
+    "pre-link-args": ["-m32", "-nostdlib", "-static"],
+    "features": "+soft-float",
+    "dynamic-linking": false,
+    "executables": true,
+    "relocation-model": "static",
+    "code-model": "default",
+    "disable-redzone": true,
+    "eliminate-frame-pointer": false,
+    "exe-suffix": "",
+    "has-rpath": false,
+    "no-compiler-rt": true,
+    "no-default-libraries": true,
+    "position-independent-executables": false,
+    "has-elf-tls": true,
+    "panic-strategy": "abort"
+}

rust

@@ -1 +1 @@
-Subproject commit 6d7c2ecf2e7b73f067c093ce9770ec187f9b3ea1
+Subproject commit 57bc1a982e20524bbaac892c04e537c8f714dce6

syscall

@@ -1 +1 @@
-Subproject commit 3377a5cd2ddfd453de5ba12f064403f21f240b65
+Subproject commit a076c42403e4c51b8ee51b457f53ae9a8a7f9bb4