Work on GN toolchain definitions and build

build/toolchain/gcc_toolchain.gni

Index: build/toolchain/gcc_toolchain.gni
diff --git a/build/toolchain/gcc_toolchain.gni b/build/toolchain/gcc_toolchain.gni
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+# 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.
+
+# This template defines a GCC toolchain.
+#
+# It requires the following variables specifying the executables to run:
+#  - cc
+#  - cxx
+#  - ar
+#  - ld
+# and the following which is used in the toolchain_args
+#  - toolchain_cpu_arch  (What "cpu_arch" should be set to when invoking a
+#                         build using this toolchain.)
+#  - toolchain_os  (What "os" should be set to when invoking a build using this
+#                   toolchain.)
+template("gcc_toolchain") {
+  toolchain(target_name) {
+    # Make these apply to all tools below.
+    lib_prefix = "-l"
+    lib_dir_prefix="-L"
+
+    tool("cc") {
+      # cflags_pch_c
+      command = "$cc -MMD -MF \$out.d \$defines \$includes \$cflags \$cflags_c -c \$in -o \$out"
+      description = "CC \$out"
+      depfile = "\$out.d"
+      deps = "gcc"
+    }
+    tool("cxx") {
+      # cflags_pch_cc
+      command = "$cxx -MMD -MF \$out.d \$defines \$includes \$cflags \$cflags_cc -c \$in -o \$out"
+      description = "CXX \$out"
+      depfile = "\$out.d"
+      deps = "gcc"
+    }
+    tool("alink") {
+      command = "rm -f \$out && $ar rcs \$out \$in"
+      description = "AR \$out"
+    }
+    tool("solink") {
+      command = "if [ ! -e \$lib -o ! -e \${lib}.TOC ]; then $ld -shared \$ldflags -o \$lib -Wl,-soname=\$soname -Wl,--whole-archive \$in \$solibs -Wl,--no-whole-archive \$libs && { readelf -d \${lib} | grep SONAME ; nm -gD -f p \${lib} | cut -f1-2 -d' '; } > \${lib}.TOC; else $ld -shared \$ldflags -o \$lib -Wl,-soname=\$soname -Wl,--whole-archive \$in \$solibs -Wl,--no-whole-archive \$libs && { readelf -d \${lib} | grep SONAME ; nm -gD -f p \${lib} | cut -f1-2 -d' '; } > \${lib}.tmp && if ! cmp -s \${lib}.tmp \${lib}.TOC; then mv \${lib}.tmp \${lib}.TOC ; fi; fi"
+      description = "SOLINK \$lib"
+      #pool = "link_pool"
+      restat = "1"
+    }
+    tool("link") {
+      command = "$ld \$ldflags -o \$out -Wl,--start-group \$in \$solibs -Wl,--end-group \$libs"
+      description = "LINK \$out"
+      #pool = "link_pool"
+    }
+    tool("stamp") {
+      command = "\${postbuilds}touch \$out"
+      description = "STAMP \$out"
+    }
+    tool("copy") {
+      command = "ln -f \$in \$out 2>/dev/null || (rm -rf \$out && cp -af \$in \$out)"
+      description = "COPY \$in \$out"
+    }
+
+    # When invoking this toolchain not as the default one, these args will be
+    # passed to the build. They are ignored when this is the default toolchain.
+    toolchain_args() {
+      cpu_arch = toolchain_cpu_arch
+      os = toolchain_os
+    }
+  }
+}