Rename run_hooks.py to setup.py

Moves 'gn gen' into setup.py

Make tools/build.py more ergonomic.

tools/setup.py

@@ -0,0 +1,53 @@
+#!/usr/bin/env python
+import third_party
+from util import run, build_path, build_mode
+import os
+import distutils.spawn
+
+third_party.fix_symlinks()
+third_party.download_gn()
+third_party.download_clang()
+
+
+def get_gn_args():
+    out = []
+    if build_mode() == "release":
+        out += ["is_official_build=true"]
+    elif build_mode() == "debug":
+        pass
+    else:
+        print "Bad mode {}. Use 'release' or 'debug' (default)" % build_mode()
+        sys.exit(1)
+    if "DENO_BUILD_ARGS" in os.environ:
+        out += os.environ["DENO_BUILD_ARGS"].split()
+
+    # Check if ccache is in the path, and if so we cc_wrapper.
+    ccache_path = distutils.spawn.find_executable("ccache")
+    if ccache_path:
+        out += [r'cc_wrapper="%s"' % ccache_path]
+
+    print "DENO_BUILD_ARGS:", out
+
+    return out
+
+
+# gn gen.
+for mode in ["release", "debug"]:
+    os.environ["DENO_BUILD_MODE"] = mode
+
+    gn_args = get_gn_args()
+
+    # mkdir $build_path(). We do this so we can write args.gn before running gn gen.
+    if not os.path.isdir(build_path()):
+        os.makedirs(build_path())
+
+    # Rather than using gn gen --args we manually write the args.gn override file.
+    # This is to avoid quoting/escaping complications when passing overrides as
+    # command-line arguments.
+    args_filename = os.path.join(build_path(), "args.gn")
+    if not os.path.exists(args_filename) or gn_args:
+        with open(args_filename, "w+") as f:
+            f.write("\n".join(gn_args) + "\n")
+
+    run([third_party.gn_path, "gen", build_path()],
+        env=third_party.google_env())