Create toolchainBionic for the various bionic-based toolchains to inherit from

Host bionic and each of the device bionic architectures will share some
new toolchain functionality in common, create a toolchainBionic and embed
it into the toolchains.  Use it to implement Bionic() once and change
the default implementation from true to false.

Test: go test ./cc/...
Test: m checkbuild
Change-Id: Ia34b80d9691edc4ab1cbdbd005d1ffc950d0881c

cc/config/Android.bp

@@ -17,6 +17,8 @@ bootstrap_go_package {
         "toolchain.go",
         "vndk.go",
 
+        "bionic.go",
+
         "arm_device.go",
         "arm64_device.go",
         "arm64_fuchsia_device.go",