BPF: rename bpf_defaults to bpf_cc_defaults

With the addition of defaults to the bpf soong module (see aosp/3249485
), the name `bpf_defaults` will be used to define defaults for bpf
program compilation. While there are separate soong namespaces for
module types and module names, rename the existing bpf_defaults
cc_defaults to bpf_cc_defaults for clarity.

While we're at it, add -Wextra, and cleanup unnecessary cflags in
clauses which use bpf_cc_defaults.

Test: TH
Change-Id: Ia6e69a7ae447490ddc7bc3e08f2d07753bae0eac
Signed-off-by: Neill Kapron <nkapron@google.com>

Android.bp

@@ -16,10 +16,11 @@ license {
 }
 
 cc_defaults {
-    name: "bpf_defaults",
+    name: "bpf_cc_defaults",
     cflags: [
         "-Wall",
         "-Werror",
+        "-Wextra",
         "-Wnullable-to-nonnull-conversion",
         "-Wthread-safety",
         "-Wunused-parameter",

loader/Android.bp

@@ -37,7 +37,6 @@ cc_library {
             },
         },
     },
-
     shared_libs: [
         "libbase",
         "libutils",
@@ -50,13 +49,7 @@ cc_library {
         "bpf_headers",
     ],
     export_include_dirs: ["include"],
-
-    defaults: ["bpf_defaults"],
-    cflags: [
-        "-Werror",
-        "-Wall",
-        "-Wextra",
-    ],
+    defaults: ["bpf_cc_defaults"],
 }
 
 rust_bindgen {
@@ -88,10 +81,8 @@ cc_test {
     srcs: [
         "BpfLoadTest.cpp",
     ],
-    defaults: ["bpf_defaults"],
+    defaults: ["bpf_cc_defaults"],
     cflags: [
-        "-Wall",
-        "-Werror",
         "-Wno-error=unused-variable",
     ],
     static_libs: [