test: Add imports for util bpf_cflags

This is required for the next commit.

Github-Pull: #32336
Rebased-From: fa0c1baaf8

test/functional/test_framework/util.py

@@ -277,6 +277,13 @@ def wait_until_helper_internal(predicate, *, attempts=float('inf'), timeout=floa
     raise RuntimeError('Unreachable')
 
 
+def bpf_cflags():
+    return [
+        "-Wno-error=implicit-function-declaration",
+        "-Wno-duplicate-decl-specifier",  # https://github.com/bitcoin/bitcoin/issues/32322
+    ]
+
+
 def sha256sum_file(filename):
     h = hashlib.sha256()
     with open(filename, 'rb') as f: