build: remove the vendor directory (#28883)

The `vendor` directory is a remnant of times long since gone when we had
brightray and libchromiumcontent (never forget).  It is currently the
hope to a single header file that afaics we do not need anymore and
randomly pyyaml gets cloned there but that is easily movable.

This commit removes all references to the vendor directory from scripts,
docs, helpers, etc. and removes the directory itself.

script/lib/config.py

@@ -4,18 +4,6 @@ from __future__ import print_function
 import os
 import sys
 
-# URL to the mips64el sysroot image.
-MIPS64EL_SYSROOT_URL = 'https://github.com/electron' \
-                     + '/debian-sysroot-image-creator/releases/download' \
-                     + '/v0.5.0/debian_jessie_mips64-sysroot.tar.bz2'
-# URL to the mips64el toolchain.
-MIPS64EL_GCC = 'gcc-4.8.3-d197-n64-loongson'
-MIPS64EL_GCC_URL = 'http://ftp.loongnix.org/toolchain/gcc/release/' \
-                 + MIPS64EL_GCC + '.tar.gz'
-
-BASE_URL = os.getenv('LIBCHROMIUMCONTENT_MIRROR') or \
-    'https://s3.amazonaws.com/github-janky-artifacts/libchromiumcontent'
-
 PLATFORM = {
   'cygwin': 'win32',
   'darwin': 'darwin',
@@ -92,22 +80,3 @@ def get_zip_name(name, version, suffix=''):
   if suffix:
     zip_name += '-' + suffix
   return zip_name + '.zip'
-
-
-def build_env():
-  env = os.environ.copy()
-  if get_target_arch() == "mips64el":
-    SOURCE_ROOT = os.path.abspath(os.path.dirname(
-                    os.path.dirname(os.path.dirname(__file__))))
-    VENDOR_DIR = os.path.join(SOURCE_ROOT, 'vendor')
-    gcc_dir = os.path.join(VENDOR_DIR, MIPS64EL_GCC)
-    ldlib_dirs = [
-      gcc_dir + '/usr/x86_64-unknown-linux-gnu/mips64el-redhat-linux/lib',
-      gcc_dir + '/usr/lib64',
-      gcc_dir + '/usr/mips64el-redhat-linux/lib64',
-      gcc_dir + '/usr/mips64el-redhat-linux/sysroot/lib64',
-      gcc_dir + '/usr/mips64el-redhat-linux/sysroot/usr/lib64',
-    ]
-    env['LD_LIBRARY_PATH'] = os.pathsep.join(ldlib_dirs)
-    env['PATH'] = os.pathsep.join([gcc_dir + '/usr/bin', env['PATH']])
-  return env