Remove JavaCpuSupplier; use the actual --cpu value instead.

This is a semantic change for Bazel, which now observes the --cpu flag when
looking up a Jvm. Use "-default" as a fallback to keep the change backwards
compatible.

RELNOTES[INC]: Bazel now uses the --cpu flag to look up Jvms; it falls back
    to "default" if it can't find a Jvm matching the CPU value.

--
MOS_MIGRATED_REVID=135333759
diff --git a/tools/jdk/BUILD b/tools/jdk/BUILD
index 5ec7ec6..22d26eb 100644
--- a/tools/jdk/BUILD
+++ b/tools/jdk/BUILD
@@ -20,39 +20,39 @@
     }),
 )
 
-filegroup(
+alias(
     name = "jni_header",
-    srcs = ["//external:jni_header"],
+    actual = "//external:jni_header",
 )
 
-filegroup(
+alias(
     name = "jni_md_header-darwin",
-    srcs = ["//external:jni_md_header-darwin"],
+    actual = "//external:jni_md_header-darwin",
 )
 
-filegroup(
+alias(
     name = "jni_md_header-linux",
-    srcs = ["//external:jni_md_header-linux"],
+    actual = "//external:jni_md_header-linux",
 )
 
-filegroup(
+alias(
     name = "jni_md_header-freebsd",
-    srcs = ["//external:jni_md_header-freebsd"],
+    actual = "//external:jni_md_header-freebsd",
 )
 
-filegroup(
+alias(
     name = "java",
-    srcs = ["//external:java"],
+    actual = "//external:java",
 )
 
-filegroup(
+alias(
     name = "jar",
-    srcs = ["//external:jar"],
+    actual = "//external:jar",
 )
 
-filegroup(
+alias(
     name = "javac",
-    srcs = ["//external:javac"],
+    actual = "//external:javac",
 )
 
 # On Windows, executables end in ".exe", but the label we reach it through
@@ -71,14 +71,14 @@
     "charsets.jar",
 ]
 
-filegroup(
+alias(
     name = "bootclasspath",
-    srcs = ["//external:bootclasspath"],
+    actual = "//external:bootclasspath",
 )
 
-filegroup(
+alias(
     name = "extdir",
-    srcs = ["//external:extdir"],
+    actual = "//external:extdir",
 )
 
 filegroup(
@@ -92,26 +92,14 @@
     neverlink = 1,
 )
 
-# This one is just needed because of how filegroup redirection works.
-filegroup(name = "jre-null")
-
-filegroup(
+alias(
     name = "jre",
-    srcs = [
-        ":jre-null",
-        "//external:jre-default",
-    ],
+    actual = "//external:jre",
 )
 
-# This one is just needed because of how filegroup redirection works.
-filegroup(name = "jdk-null")
-
-filegroup(
+alias(
     name = "jdk",
-    srcs = [
-        ":jdk-null",
-        "//external:jdk-default",
-    ],
+    actual = "//external:jdk",
 )
 
 java_toolchain(