Replace x86_64-sun-solaris with x86_64-pc-solaris

rust-lang/rust#82216 removed the
x86_64-sun-solaris target from rustup, changing it to use
x86_64-pc-solaris instead.

Related issues:
 * rust-lang/rust#85098

.github/workflows/main.yml

@@ -63,7 +63,7 @@ jobs:
       matrix:
         # TODO: add the following targets, currently broken.
         # "x86_64-unknown-redox"
-        target: ["aarch64-apple-ios", "aarch64-linux-android", "x86_64-apple-darwin", "x86_64-fuchsia", "x86_64-pc-windows-msvc", "x86_64-sun-solaris", "x86_64-unknown-illumos", "x86_64-unknown-linux-gnu", "x86_64-unknown-netbsd"]
+        target: ["aarch64-apple-ios", "aarch64-linux-android", "x86_64-apple-darwin", "x86_64-fuchsia", "x86_64-pc-windows-msvc", "x86_64-pc-solaris", "x86_64-unknown-illumos", "x86_64-unknown-linux-gnu", "x86_64-unknown-netbsd"]
     steps:
     - uses: actions/checkout@master
     - name: Install Rust

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-fuchsia" "x86_64-pc-windows-msvc" "x86_64-sun-solaris" "x86_64-unknown-freebsd" "x86_64-unknown-illumos" "x86_64-unknown-linux-gnu" "x86_64-unknown-netbsd" "x86_64-unknown-redox"
+TARGETS ?= "aarch64-apple-ios" "aarch64-linux-android" "x86_64-apple-darwin" "x86_64-fuchsia" "x86_64-pc-windows-msvc" "x86_64-pc-solaris" "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