Add parallel make toolchain wrapper

This can be used by adding
`--extra_toolchains=@rules_foreign_cc//toolchains:built_make_parallel_toolchain` to your bazel command line

Addresses some of bazelbuild#329

examples/WORKSPACE.bazel

@@ -18,9 +18,9 @@ load("//deps:repositories.bzl", "repositories")
 
 repositories()
 
-load("//deps:deps_android.bzl", "deps_android")
+#load("//deps:deps_android.bzl", "deps_android")
 
-deps_android()
+#deps_android()
 
 load("//deps:deps_jvm_external.bzl", "deps_jvm_external")
 

foreign_cc/private/framework.bzl

@@ -483,6 +483,7 @@ def cc_external_rule_impl(ctx, attrs):
             ctx.files.build_data +
             legacy_tools +
             cc_toolchain.all_files.to_list() +
+	    inputs.tool_runfiles +
             tool_runfiles +
             [data[DefaultInfo].files_to_run for data in data_dependencies],
         command = wrapped_outputs.wrapper_script_file.path,
@@ -784,6 +785,7 @@ InputFiles = provider(
             "Files and directories with tools needed for configuration/building " +
             "to be copied into the bin folder, which is added to the PATH"
         ),
+        tool_runfiles = "All files and directories that must be declared as runfiles for tools",
         ext_build_dirs = (
             "Directories with libraries, built by framework function. " +
             "This directories should be copied into $EXT_BUILD_DEPS/lib-name as is, with all contents."
@@ -825,15 +827,18 @@ def _define_inputs(attrs):
 
     tools_roots = []
     tools_files = []
+    tool_runfiles = []
     input_files = []
     for tool in attrs.tools_deps:
+        tool_runfiles += tool[DefaultInfo].default_runfiles.files.to_list()
         tool_root = detect_root(tool)
         tools_roots.append(tool_root)
         for file_list in tool.files.to_list():
             tools_files += _list(file_list)
 
     # TODO: Remove, `additional_tools` is deprecated.
     for tool in attrs.additional_tools:
+        tool_runfiles += tool[DefaultInfo].default_runfiles.files.to_list()
         for file_list in tool.files.to_list():
             tools_files += _list(file_list)
 
@@ -853,6 +858,7 @@ def _define_inputs(attrs):
         deps_compilation_info = cc_info_merged.compilation_context,
         deps_linking_info = cc_info_merged.linking_context,
         ext_build_dirs = ext_build_dirs,
+	tool_runfiles = tool_runfiles,
         declared_inputs = filter_containing_dirs_from_inputs(attrs.lib_source.files.to_list()) +
                           bazel_libs +
                           tools_files +

toolchains/BUILD.bazel

@@ -81,6 +81,12 @@ toolchain(
     toolchain_type = ":make_toolchain",
 )
 
+toolchain(
+    name = "built_make_parallel_toolchain",
+    toolchain = ":built_parallel_make",
+    toolchain_type = ":make_toolchain",
+)
+
 # Preinstalled cmake will always be the default, if toolchain with more exact constraints
 # is not defined before; registered from workspace_definitions.bzl#rules_foreign_cc_dependencies
 toolchain(
@@ -146,6 +152,19 @@ native_tool_toolchain(
     target = ":make_tool",
 )
 
+sh_binary(
+    name = "parallel_make",
+    srcs = ["parallel_make.sh"],
+    data = [":make_tool"],
+    deps = ["@bazel_tools//tools/bash/runfiles"],
+)
+
+native_tool_toolchain(
+    name = "built_parallel_make",
+    path = "parallel_make",
+    target = ":parallel_make",
+)
+
 native_tool_toolchain(
     name = "preinstalled_cmake",
     env = select({

toolchains/parallel_make.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+pushd $EXT_BUILD_ROOT/external
+
+# --- begin runfiles.bash initialization v2 ---
+# Copy-pasted from the Bazel Bash runfiles library v2.
+set -uo pipefail; f=bazel_tools/tools/bash/runfiles/runfiles.bash
+source "${RUNFILES_DIR:-/dev/null}/$f" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "${RUNFILES_MANIFEST_FILE:-/dev/null}" | cut -f2- -d' ')" 2>/dev/null || \
+  source "$0.runfiles/$f" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "$0.runfiles_manifest" | cut -f2- -d' ')" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "$0.exe.runfiles_manifest" | cut -f2- -d' ')" 2>/dev/null || \
+  { echo>&2 "ERROR: cannot find $f"; exit 1; }; f=; set -e
+# --- end runfiles.bash initialization v2 ---
+
+popd
+
+NUMBER_OF_CPUS=$(nproc)
+exec "$(rlocation rules_foreign_cc/toolchains/make/bin/make)" -j${NUMBER_OF_CPUS} -l${NUMBER_OF_CPUS} "$@"