Add more targets to Makefile

Adds:
 * arm-linux-androideabi
 * i686-unknown-linux-gnu
 * x86_64-apple-ios
 * x86_64-unknown-redox

Since we use this in GitHub Actions we'll need to match the targets of
Azure CI.

.github/workflows/ci.yml

@@ -1,9 +1,9 @@
 name: CI
 on:
   push:
-    branches: [ master ]
+    branches: [ "master" ]
   pull_request:
-    branches: [ master ]
+    branches: [ "master" ]
 env:
   CARGO_TERM_COLOR: always
   RUST_BACKTRACE: full
@@ -15,7 +15,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: ["ubuntu-latest", "macos-latest", "windows-latest"]
     steps:
     - uses: actions/checkout@v2
     - uses: actions-rs/toolchain@v1
@@ -35,7 +35,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: ["ubuntu-latest", "macos-latest", "windows-latest"]
     steps:
     - uses: actions/checkout@v2
     - uses: actions-rs/toolchain@v1

Makefile

@@ -1,5 +1,5 @@
 # Targets available via Rustup that are supported.
-TARGETS ?= aarch64-apple-ios aarch64-linux-android x86_64-apple-darwin x86_64-pc-windows-msvc x86_64-unknown-freebsd x86_64-unknown-illumos x86_64-unknown-linux-gnu x86_64-unknown-netbsd
+TARGETS ?= aarch64-apple-ios aarch64-linux-android arm-linux-androideabi i686-unknown-linux-gnu x86_64-apple-darwin x86_64-apple-ios x86_64-pc-windows-msvc x86_64-unknown-freebsd x86_64-unknown-illumos x86_64-unknown-linux-gnu x86_64-unknown-netbsd x86_64-unknown-redox
 
 test:
 	cargo test --all-features