Add some NetBSD target to toolchain prefix mappings

- arm-unknown-netbsdelf-eabi
 - armv6-unknown-netbsdelf-eabihf
 - armv7-unknown-netbsdelf-eabihf
 - i686-unknown-netbsdelf
 - powerpc-unknown-netbsd
 - x86_64-unknown-netbsd

src/lib.rs

@@ -677,17 +677,23 @@ impl Config {
                     "arm-unknown-linux-gnueabihf"  => Some("arm-linux-gnueabihf"),
                     "arm-unknown-linux-musleabi" => Some("arm-linux-musleabi"),
                     "arm-unknown-linux-musleabihf"  => Some("arm-linux-musleabihf"),
+                    "arm-unknown-netbsdelf-eabi" => Some("arm--netbsdelf-eabi"),
+                    "armv6-unknown-netbsdelf-eabihf" => Some("armv6--netbsdelf-eabihf"),
                     "armv7-unknown-linux-gnueabihf" => Some("arm-linux-gnueabihf"),
                     "armv7-unknown-linux-musleabihf" => Some("arm-linux-musleabihf"),
+                    "armv7-unknown-netbsdelf-eabihf" => Some("armv7--netbsdelf-eabihf"),
                     "i686-pc-windows-gnu" => Some("i686-w64-mingw32"),
+                    "i686-unknown-netbsdelf" => Some("i486--netbsdelf"),
                     "mips-unknown-linux-gnu" => Some("mips-linux-gnu"),
                     "mipsel-unknown-linux-gnu" => Some("mipsel-linux-gnu"),
                     "powerpc-unknown-linux-gnu" => Some("powerpc-linux-gnu"),
+                    "powerpc-unknown-netbsd" => Some("powerpc--netbsd"),
                     "powerpc64-unknown-linux-gnu" => Some("powerpc-linux-gnu"),
                     "powerpc64le-unknown-linux-gnu" => Some("powerpc64le-linux-gnu"),
                     "x86_64-pc-windows-gnu" => Some("x86_64-w64-mingw32"),
                     "x86_64-rumprun-netbsd" => Some("x86_64-rumprun-netbsd"),
                     "x86_64-unknown-linux-musl" => Some("musl"),
+                    "x86_64-unknown-netbsd" => Some("x86_64--netbsd"),
                     _ => None,
                 };
                 match prefix {