[infra] Fixes for cross-toolchains

build/toolchain/linux/BUILD.gn

 # Copyright 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.
 
 import("//build/config/sysroot.gni")
 import("//build/toolchain/ccache.gni")
 import("//build/toolchain/clang.gni")
 import("//build/toolchain/gcc_toolchain.gni")
 import("//build/toolchain/goma.gni")
 
 declare_args() {
   toolchain_prefix = ""
 }
 
 if (use_goma) {
   assert(!use_ccache, "Goma and ccache can't be used together.")
   compiler_prefix = "$goma_dir/gomacc "
 } else if (use_ccache) {
   compiler_prefix = "ccache "
 } else {
   compiler_prefix = ""
 }
 
 gcc_toolchain("arm") {
-  cc = "${compiler_prefix}arm-linux-gnueabihf-gcc"
-  cxx = "${compiler_prefix}arm-linux-gnueabihf-g++"
+  prefix = "arm-linux-gnueabihf-"
+  if (toolchain_prefix != "") {
+    prefix = toolchain_prefix
+  }
 
-  ar = "arm-linux-gnueabihf-ar"
+  cc = "${compiler_prefix}${prefix}gcc"
+  cxx = "${compiler_prefix}${prefix}g++"
+
+  ar = "${prefix}ar"
   ld = cxx
-  readelf = "arm-linux-gnueabihf-readelf"
-  nm = "arm-linux-gnueabihf-nm"
+  readelf = "${prefix}readelf"
+  nm = "${prefix}nm"
 
   toolchain_cpu = "arm"
   toolchain_os = "linux"
   is_clang = false
 }
 
 gcc_toolchain("arm64") {
-  cc = "${compiler_prefix}aarch64-linux-gnu-gcc"
-  cxx = "${compiler_prefix}aarch64-linux-gnu-g++"
+  prefix = "aarch64-linux-gnu-"
+  if (toolchain_prefix != "") {
+    prefix = toolchain_prefix
+  }
 
-  ar = "aarch64-linux-gnu-ar"
+  cc = "${compiler_prefix}${prefix}gcc"
+  cxx = "${compiler_prefix}${prefix}g++"
+
+  ar = "${prefix}ar"
   ld = cxx
-  readelf = "aarch64-linux-gnu-readelf"
-  nm = "aarch64-linux-gnu-nm"
+  readelf = "${prefix}readelf"
+  nm = "${prefix}nm"
 
   toolchain_cpu = "arm64"
   toolchain_os = "linux"
   is_clang = false
 }
 
 gcc_toolchain("clang_x86") {
   prefix = rebase_path("//third_party/llvm-build/Release+Asserts/bin",
                        root_build_dir)
   cc = "${compiler_prefix}$prefix/clang"
@@ skipping 46 matching lines @@
   nm = "nm"
   ar = "ar"
   ld = cxx
 
   toolchain_cpu = "x64"
   toolchain_os = "linux"
   is_clang = false
 }
 
 gcc_toolchain("mipsel") {
-  cc = "${toolchain_prefix}gcc"
-  cxx = "${toolchain_prefix}g++"
+  cc = "${compiler_prefix}${toolchain_prefix}gcc"
+  cxx = "${compiler_prefix}${toolchain_prefix}g++"
   ar = "${toolchain_prefix}ar"
   ld = cxx
   readelf = "${toolchain_prefix}readelf"
   nm = "${toolchain_prefix}nm"
 
   toolchain_cpu = "${target_cpu}"
   toolchain_os = "linux"
   is_clang = is_clang
 }