Fix GN toolchains to use proper out dir.

build/toolchain/mac/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # TODO(brettw) Use "gcc_toolchain.gni" like the Linux toolchains. This requires
 # some enhancements since the commands on Mac are slightly different than on
 # Linux.
 
 import("../goma.gni")
 
@@ skipping 99 matching lines @@
       command = "rm -f {{output}} && ./gyp-mac-tool filter-libtool libtool -static -o {{output}} {{inputs}}"
       description = "LIBTOOL-STATIC {{output}}"
       outputs = [
         "{{target_out_dir}}/{{target_output_name}}{{output_extension}}"
       ]
       default_output_extension = ".a"
       output_prefix = "lib"
     }
 
     tool("solink") {
-      dylib = "{{target_output_name}}{{output_extension}}"  # eg "libfoo.dylib"
+      dylib = "{{root_out_dir}}/{{target_output_name}}{{output_extension}}"  # eg "./libfoo.dylib"
       rspfile = dylib + ".rsp"
 
       # These variables are not build into GN but are helpers that implement
       # (1) linking to produce a .so, (2) extracting the symbols from that file
       # to a temporary file, (3) if the temporary file has differences from the
       # existing .TOC file, overwrite it, oterwise, don't change it.
       #
       # As a special case, if the library reexports symbols from other dynamic
       # libraries, we always update the .TOC and skip the temporary file and
       # diffing steps, since that library always needs to be re-linked.
@@ skipping 27 matching lines @@
       # tocname for dependency management.
       outputs = [
         dylib,
         tocname,
       ]
       link_output = dylib
       depend_output = tocname
     }
 
     tool("link") {
-      outfile = "{{target_output_name}}{{output_extension}}"
+      outfile = "{{root_out_dir}}/{{target_output_name}}{{output_extension}}"
       rspfile = "$outfile.rsp"
       command = "$ld {{ldflags}} -o $outfile -Wl,-filelist,$rspfile {{solibs}} {{libs}}"
       description = "LINK $outfile"
       rspfile_content = "{{inputs_newline}}"
       outputs = [ outfile ]
     }
 
     tool("stamp") {
       command = "touch {{output}}"
       description = "STAMP {{output}}"
@@ skipping 13 matching lines @@
 # Toolchain representing the target build (either mac or iOS).
 mac_clang_toolchain("clang") {
   toolchain_os = os
 }
 
 # This toolchain provides a way for iOS target compiles to reference targets
 # compiled for the host system. It just overrides the OS back to "mac".
 mac_clang_toolchain("host_clang") {
   toolchain_os = "mac"
 }