C++: Move to new packaging rules.

cpp/downgrades/BUILD.bazel

@@ -6,7 +6,7 @@ pkg_files(
         ["**"],
         exclude = ["BUILD.bazel"],
     ),
-    prefix = "cpp/downgrades",
+    prefix = "downgrades",
     strip_prefix = strip_prefix.from_pkg(),
     visibility = ["//cpp:__pkg__"],
 )

cpp/ql/lib/BUILD.bazel

@@ -5,11 +5,9 @@ package(default_visibility = ["//cpp:__pkg__"])
 pkg_files(
     name = "dbscheme",
     srcs = ["semmlecode.cpp.dbscheme"],
-    prefix = "cpp",
 )
 
 pkg_files(
     name = "dbscheme-stats",
     srcs = ["semmlecode.cpp.dbscheme.stats"],
-    prefix = "cpp",
 )

csharp/autobuilder/Semmle.Autobuild.Cpp/BUILD.bazel

@@ -9,7 +9,6 @@ codeql_csharp_binary(
         "*.cs",
         "Properties/*.cs",
     ]),
-    language_prefix = "cpp",
     visibility = ["//visibility:public"],
     deps = [
         "//csharp/autobuilder/Semmle.Autobuild.Shared",

misc/bazel/csharp.bzl

@@ -33,7 +33,7 @@ def codeql_xunit_test(name, **kwargs):
         **kwargs
     )
 
-def codeql_csharp_binary(name, language_prefix = "csharp", **kwargs):
+def codeql_csharp_binary(name, **kwargs):
     kwargs.setdefault("nullable", "enable")
     kwargs.setdefault("target_frameworks", [TARGET_FRAMEWORK])