Auto merge of rust-lang#31074 - gmbonnet:stage0-libdir, r=alexcrichton

This fixes rust-lang#27254.

On a 64-bit Linux machine, for example, `configure --libdir=/usr/local/lib64` was creating both `x86_64-unknown-linux-gnu/stage0/lib/rustlib` and `x86_64-unknown-linux-gnu/stage0/lib64/rustlib`. Crates from the stage0 snapshot, like `libcore`, are extracted to `x86_64-unknown-linux-gnu/stage0/lib/rustlib`, but the stage0 compiler was attempting to find them in `x86_64-unknown-linux-gnu/stage0/lib64/rustlib`, which has the highest priority on a 64-bit system.

The issue can be fixed by creating only `x86_64-unknown-linux-gnu/stage0/lib/rustlib`, since this is the only rustlib directory needed for stage0 anyways.

Author: bors

configure

@@ -1361,16 +1361,22 @@ for h in $CFG_HOST
 do
     for t in $CFG_TARGET
     do
+        # host bin dir stage0
+        make_dir $h/stage0/bin
+
         # host lib dir stage0
         make_dir $h/stage0/lib
 
+        # host test dir stage0
+        make_dir $h/stage0/test
+
         # target bin dir stage0
         make_dir $h/stage0/lib/rustlib/$t/bin
 
         # target lib dir stage0
         make_dir $h/stage0/lib/rustlib/$t/lib
 
-        for i in 0 1 2 3
+        for i in 1 2 3
         do
             # host bin dir
             make_dir $h/stage$i/bin