Don't use @local_jdk for jni headers

instead, read the heads from the configured java runtime, so the values
track with changes to --javabase.

See bazelbuild#5594

PiperOrigin-RevId: 207894086

Author: cushon

tools/jdk/BUILD

@@ -3,6 +3,7 @@ package(default_visibility = ["//visibility:public"])
 load(
     "//tools/jdk:default_java_toolchain.bzl",
     "default_java_toolchain",
+    "java_runtime_files",
     "DEFAULT_JAVACOPTS",
 )
 
@@ -32,29 +33,29 @@ alias(
     actual = "@bazel_tools//tools/jdk:current_java_runtime",
 )
 
-alias(
+java_runtime_files(
     name = "jni_header",
-    actual = "@local_jdk//:jni_header",
+    srcs = ["include/jni.h"],
 )
 
-alias(
+java_runtime_files(
     name = "jni_md_header-darwin",
-    actual = "@local_jdk//:jni_md_header-darwin",
+    srcs = ["include/darwin/jni_md.h"],
 )
 
-alias(
+java_runtime_files(
     name = "jni_md_header-linux",
-    actual = "@local_jdk//:jni_md_header-linux",
+    srcs = ["include/linux/jni_md.h"],
 )
 
-alias(
+java_runtime_files(
     name = "jni_md_header-windows",
-    actual = "@local_jdk//:jni_md_header-windows",
+    srcs = ["include/win32/jni_md.h"],
 )
 
-alias(
+java_runtime_files(
     name = "jni_md_header-freebsd",
-    actual = "@local_jdk//:jni_md_header-freebsd",
+    srcs = ["include/freebsd/jni_md.h"],
 )
 
 alias(

tools/jdk/default_java_toolchain.bzl

@@ -86,3 +86,19 @@ def default_java_toolchain(name, **kwargs):
         name = name,
         **toolchain_args
     )
+
+def java_runtime_files(name, srcs):
+    """Copies the given sources out of the current Java runtime."""
+
+    native.filegroup(
+        name = name,
+        srcs = srcs,
+    )
+    for src in srcs:
+        native.genrule(
+            name = "gen_%s" % src,
+            srcs = ["//tools/jdk:current_java_runtime"],
+            toolchains = ["//tools/jdk:current_java_runtime"],
+            cmd = "cp $(JAVABASE)/%s $@" % src,
+            outs = [src],
+        )