Change aarch64 build from -gnu to -musl

Close #1044

Author: autozimu

Diff for: .travis.yml

@@ -14,7 +14,7 @@ env:
 matrix:
   include:
     # Linux
-    - env: TARGETS=i686-unknown-linux-musl:x86_64-unknown-linux-musl:aarch64-unknown-linux-gnu:x86_64-pc-windows-gnu
+    - env: TARGETS=i686-unknown-linux-musl:x86_64-unknown-linux-musl:aarch64-unknown-linux-musl:x86_64-pc-windows-gnu
 
     # OSX
     - env: TARGETS=x86_64-apple-darwin

Diff for: install.sh

@@ -55,7 +55,7 @@ fi
 case "${arch}" in
     "Linux x86_64") download $name-$version-x86_64-unknown-linux-musl ;;
     "Linux i686") download $name-$version-i686-unknown-linux-musl ;;
-    "Linux aarch64") download $name-$version-aarch64-unknown-linux-gnu ;;
+    "Linux aarch64") download $name-$version-aarch64-unknown-linux-musl ;;
     "Darwin x86_64") download $name-$version-x86_64-apple-darwin ;;
     "FreeBSD amd64") download $name-$version-x86_64-unknown-freebsd ;;
     *) echo "No pre-built binary available for ${arch}."; try_build ;;