Revert of [NaCl SDK] Remove support for bionic toolchain

native_client_sdk/src/build_tools/build_projects.py

Index: native_client_sdk/src/build_tools/build_projects.py
diff --git a/native_client_sdk/src/build_tools/build_projects.py b/native_client_sdk/src/build_tools/build_projects.py
index f1a76c23686687c97db0e02fc936c17fbfea722f..0c5077a6534d24ae760dbdd43c8903d19794c0c8 100755
--- a/native_client_sdk/src/build_tools/build_projects.py
+++ b/native_client_sdk/src/build_tools/build_projects.py
@@ -30,6 +30,7 @@
   'win': ['x86_32']
 }
 VALID_TOOLCHAINS = [
+  'bionic',
   'newlib',
   'clang-newlib',
   'glibc',
@@ -212,6 +213,10 @@
   make_cmd = [make, '-j', jobs]
 
   make_cmd.append('CONFIG='+config)
+  # We always ENABLE_BIONIC in case we need it.  If neither --bionic nor
+  # -t bionic have been provided on the command line, then VALID_TOOLCHAINS
+  # will not contain a bionic target.
+  make_cmd.append('ENABLE_BIONIC=1')
   if not deps:
     make_cmd.append('IGNORE_DEPS=1')
 
@@ -251,6 +256,8 @@
   parser.add_argument('--config',
       help='Choose configuration to build (Debug or Release).  Builds both '
            'by default')
+  parser.add_argument('--bionic',
+      help='Enable bionic projects', action='store_true')
   parser.add_argument('-x', '--experimental',
       help='Build experimental projects', action='store_true')
   parser.add_argument('-t', '--toolchain',
@@ -294,6 +301,8 @@
     # e.g. If an example supports newlib and glibc, then the default will be
     # newlib.
     options.toolchain = ['pnacl', 'newlib', 'glibc', 'host', 'clang-newlib']
+    if options.experimental or options.bionic:
+      options.toolchain.append('bionic')
 
   if 'host' in options.toolchain:
     options.toolchain.remove('host')