Add a bunch more cargo cross builds

Author: alexcrichton

master/master.cfg

@@ -228,6 +228,14 @@ cargo_cross_targets = [
   'x86_64-unknown-freebsd',
   'x86_64-unknown-netbsd',
   'i686-unknown-freebsd',
+  'mips-unknown-linux-gnu',
+  'mipsel-unknown-linux-gnu',
+  'mips64-unknown-linux-gnuabi64',
+  'mips64el-unknown-linux-gnuabi64',
+  's390x-unknown-linux-gnu',
+  'powerpc-unknown-linux-gnu',
+  'powerpc64-unknown-linux-gnu',
+  'powerpc64le-unknown-linux-gnu',
 ]
 
 ios = {'auto': 'cross-ios-opt', 'dist': 'mac-ios'}